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INDEX
Preface
What is a Reef Tank?
Types of Reef Tanks
Choosing Your Suppliers
Tank Selection
Lighting
Filtration
Substrate
Making Saltwater
Nitrogen Cycle
Salinity
Temperature
Water Chemistry
Alkalinity / Calcium
Iodine
pH
Water Changes
Test Kits
Acclimation
Introduction to fishes
Introduction to Mobile Invertebrates
Introduction to Clams
Introduction to Soft Corals
Introduction to Large Polyp Stony (LPS) Corals
Introduction to Small Polyp Stony (SPS) Corals
Feeding
SPS Coloration
Specimens to Avoid
When Good Things Go Bad
Preface
There are many books available that give instructions on the basics and theory of reef keeping. In general, they try to be everything to everyone and in the process they keep their information so general as to be almost useless. Too much unfiltered information is almost as bad as no information at all. Worse yet, many of these books are seriously outdated in a hobby that makes new breakthroughs every year. They hype the latest fad that was in vogue at the time of publishing. This manual takes the opposite approach. It is the filtered version. It is light on theory and heavy on specifics. Theory is explored just in as much detail as is important to keeping a successful reef tank. I have made the assumption that most individuals who are reading this manual also have at least one standard book on reef keeping which fills in any gaps in this theoretical knowledge. I will provide links to important technical documents where appropriate for those who would like more in-depth reading on particular subjects.
The other reason for the format of this manual is simple. It is meant to supplement and if necessary replace the knowledgeable pet store that sells reef supplies. Such stores are far too scarce and individuals often make the mistake of assuming that if a store sells reef supplies, the store personnel must know what they are doing! Sadly, more often than not, this is not the case.
The goal of this manual is to help you establish a thriving reef tank that suits your interests.
For the uninitiated, a reef tank more than any other type of aquaria, is an enclosed ecosystem which depends on a carefully balance system that maintains high water quality and which permits the keeping of sensitive reef organisms in captivity. A reef tank, more so than any other pet hobby I am aware of, requires careful planning and maintenance to be successful. The upshot is that the potential rewards of the hobby are equally great. If you want a hobby where you can spend a few dollars to get it setup and then basically ignore the tank except to throw some dry flake food into it once a day and maybe clean the glass every week or two, then keep looking, because this is not it! However, if you want a hobby where you can really immerse yourself in it, are interested in learning some of the biology of a living reef and can invest a not insignificant amount of time in the hobby, you will probably become hooked like many of us do. Also be forewarned that this is not an inexpensive hobby. Although there are things that can be done to minimize costs somewhat, it will never be cheap.
What's a Reef Tank?
That is a good question. In general, most people are familiar with freshwater or saltwater fish only tanks, but the notion of a reef tank is a bit foreign to them. Upon first inspection, the uninitiated reaction is that a reef tank looks like a bunch of rocks with plant like things in it and an insufficient number of fish.
One major difference between a reef tank and all other types of aquaria is that a careful ecological balance must be struck among its inhabitants to maintain the proper water quality and control predation within certain boundaries.
The cornerstone of this balanced ecosystem is rock that is obtained from the ocean that harbors a myriad of life forms, which form the lower portions of this ecosystem. This rock is called ‘live rock’ based on the fact that it contains various living organisms on and within its structure. These organisms range from bacteria to sponges, fan worms, tunicates, macro algae, snails, crabs, shrimp, soft corals or even hard corals. Pretty much anything that grows on a rock in the ocean can be on the live rock when it gets introduced into the reef tank. Some of this life cannot stand the transition between ocean and tank and dies off in a process called ‘curing’ the live rock. There are also things that may come with the live rock that are not desirable, such as certain forms of algae, predatory shrimp or crabs, etc. The important thing is that live rock establishes a diversity of life forms within the tank that would be impossible to achieve through only intentional introduction of organisms.
The other element that defines a reef tank is the inclusion of corals or other reef dwelling invertebrates such as anemones. The first reaction many people have to a reef tank is “where are all the fish?”. Fish always take 2nd billing to the invertebrates in a reef tank. The reason is two-fold. One is that the fish population must be maintained within certain boundaries to keep the ecological balance. The other is that the corals or other invertebrates are really the main stars of this type of tank. If a person desires the highest possible fish density, then a fish only (FO) tank or a fish only with live rock (FOWLR) tank is the best approach to take. These tanks can be crammed (relatively speaking) with fish and mechanical filters and large water changes used to manage the waste byproducts produced by the fish to a level that keeps it within tolerance levels of the fish. This tolerance level is much higher in fish than what corals can tolerate, so this approach is not viable when corals are involved. Another consideration is that many of the popular saltwater fish cannot be placed in a reef tank because they are predators of the invertebrates or small fishes the reef tank houses or are otherwise destructive in the typical carefully landscaped reef tank.
Lastly, the inclusion of invertebrates, many of which are photosynthetic, mandates different lighting than is required in a fish only tank. They may also require supplementation of compounds in the saltwater that they require for health and growth.
Types of Reef Tanks
When setting up your first tank, it is helpful to know what your end goal is since some of the equipment required for the various setups is different. For instance, if you buy a lighting system for a soft and LPS tank and then decide you want to change to add SPS, you will probably need to upgrade your lighting, which can be expensive. Everyone goes through this, but the more that you can avoid it, the more money you will save yourself. The type of reef you want to construct will also help you to determine things like the optimum tank size to start with.
Cost may help you decide on which type of tank to setup. In general, low light, lagoon, soft and LPS coral tanks can be less expensive to setup than SPS and high light clam tanks. Nice reef tanks are never cheap to setup and you should be prepared for this. Failure in this hobby is often a result of trying to go cheap. Not to say that there are not ways to approach the hobby that are more or less expensive. Going the inexpensive route usually means limiting your inhabitants you attempt to keep.
A lot of dollars are also wasted in this hobby as well, such as buying specimens that have no chance of survival in your tank, purchasing an ineffectual protein skimmer which quickly has to be replaced, buying a lighting system only to have to upgrade it as your interest change, or buying the next great snake oil on the market for $20 a bottle.
You can also think of tanks as falling into 3 basic types.
Low demand systems
Moderate demand systems
High demand systems.
The demand level relates to the water and lighting demands of the specimens kept, the amount of effort required to maintain the system parameters and to some extent the amount of cost required to meet the demands of the specimens kept.
There are several different basic types of reef tanks that can be setup. These differences are based primarily around the types of reef critters you want to maintain, how much time you are willing to spend on the hobby and to some extent the money you are willing or able to spend on the hobby.
Low Light tank
Primary inhabitants are low light requiring corals which may or may not be photosynthetic. Typical inhabitants may include mushrooms, polyps, sun coral, non-photosynthetic gorgonians, mobile invertebrates and of course fish.
Macro algae may or may not grow depending on light intensity.
Water flow is low to moderate.
Lighting usually consists of NO fluorescent bulbs
Tank size can be small to large, but usually small
Cost is generally low, mainly due to the fact that lighting consists of relatively inexpensive lighting.
This is a low demand system in that it places a low demand on water chemistry, budget and time. Many hobbyists create this type of tank accidentally when they start in the hobby because they do not fully understand the lighting demands of many of the critters that live on the reef. Significant restrictions need to be placed on the corals that are introduced into this tank to ensure that they can survive on the available light.
Lagoon tank
Primary inhabitants are soft coral and LPS. Focus is on invertebrates that live in this reef environment. Anemones may be included if sufficient lighting is provided. This type of tank is popular for housing seahorses and pipefish.
Macro algae is usually a component of this system.
Water flow is low to simulate lagoon type conditions
Lighting of moderate to perhaps high intensity is used.Usually VHO, PC or MH.
Tank size is flexible and a small tank works well for this ecosystem
Cost is potentially low as an algal filtration is somewhat built-in.
This is a ‘Low Demand’ system
Softy and LPS tank
Primary inhabitants are soft corals and LPS with enough lighting to support any photosynthetic soft corals or LPS corals that is desired to be kept.Moderate light clams may also be included, as well as mobile invertebrates and fish. High light clams may be included in lighting intensity is high.
Macro algae is usually excluded as it may become a nuisance, but some people like the look it adds to the tank.
Water flow is moderate to simulate a reef slope condition. Wave maker may be used.
Lighting of moderate or high intensity is used depending on coral or clams types kept. Usually PC, VHO or MH
Tank size can be small to large
Cost can range from moderate to high primarily depending on the lighting system selected.
This is a ‘Moderate Demand’ system
SPS and Clam tank
Primary inhabitants are SPS corals and high light requiring clams. Although softies and LPS may be kept also, these are usually minor components of the system.
Macro algae (especially Caulerpa species) should be excluded, as it will become a nuisance. Halimeda is one of the few macro algaes that is acceptable in this type of tank.
Water flow requirements are high.Wavemaker capability is normally used to simulate reef crest conditions.
Lighting of highest intensity is used, usually Metal Halide.
Tank size tends to run on the larger side of the scale. This is mainly due to the fact that the higher cost of setup makes it more difficult to justify that cost on a small tank. Also, some items such as MH lighting tend to make more sense on larger tanks due to possible heating concerns, etc.
Cost is high due to need for high intensity lighting, high agitated water motion. Specimen cost can also be higher when dealing with SPS corals and clams, but this is not necessarily true.
This is a “High Demand” system and places the highest demands on maintaining water chemistry, budget and usually the hobbyists time.
Mixed tank
It is possible to mix and match these systems somewhat. An SPS and softie tank for instance is fairly common, although care has to be taken to ensure the inhabitants don’t start turf wars. It is also natural for some systems to evolve from one type toward another over time as the hobbyist gains experience and their interests change.
It is important to have a goal for what you want your reef tank to evolve into because the end goal will dictate your equipment and specimen selections going forward. Although it is normal to evolve your thinking as you progress in this hobby, you can save both money and frustration by taking as clear a path as possible at the onset.
One good way to do this is to find a tank that demonstrates what you want to achieve and use that as your basic model as you plan your requirements.
Choosing Suppliers
Finding a good supplier for your reef specimens is very important. There are two primary issues at hand. Do they carry quality specimens and maintain them in good health until sale and are they able to provide advice which is more helpful than harmful?
First Hand Experience
Within my local area, there were 5 pet stores that carried reef supplies. Here is a synopsis of my experiences with these stores early in my ‘formative’ years.
Pet store #1 got me started with my first reef tank. They happened to be the closest to my house and they had a nice looking reef tank on display. At least it looked like a nice reef tank to me. I had not seen any except in magazines and books. I setup my tank based upon their suggestions as well as information that I had gotten out of some fairly outdated books. I did quite a bit of research on filtration requirements and built my own wet/dry filter, bought a protein skimmer and built my own light hood based upon information in a well regarded book on reef tanks. My tank started out OK, but quickly got onto the wrong side of some serious hair algae. Specimens in the tank did not thrive. Some seemed to survive well enough, while others just faded away. Not surprisingly, that nice display tank at the pet store also fell into similar disarray. The hair algae monster took over and the tank was dismantled. So was my tank.
Pet store #2 and #3 keep a couple of fairly nice looking reef tanks that they sell specimens out of. Both tanks have low lighting to keep algae at bay and specimens mercifully wait for someone to take them home to hopefully better conditions. If a specimen stays in one of the tanks too long, it generally starts to look poor. There are of course the exceptions. These are specimens that happen to like these types of conditions.
Pet store #4 setup a large 300 gallon reef tank. This was a new pet store and I carefully watched the evolution of their display tank. The tank was setup with large amounts of live rock and large amounts of Caulerpa and yellow tangs to cycle the tank. 3 months later, the tank still had live rock, caulerpa and yellow tangs in it. 6 months later the store had closed down.
Pet store #5…. As I walked into this pet store for the first time, the first thing I saw was the most gorgeous reef tank I had ever seen. It was every bit as impressive as those pictures you see in magazines and books. This was not a tank filled with rocks and some specimens perched on them. This was a tank with virtually every surface covered with hard corals and soft corals. Xenia was growing up the glass like a weed and SPS corals had grown together over time! It was obvious that this tank has been a stable, thriving environment for years! Within 5 minutes of walking into this store, I knew I had found a pet store upon whose advice I could depend on. They had obvious unspoken proof that they knew what they are talking about. Further investigation revealed that the business was family owned and operated. All personnel there are avid reef keepers in their own right. If they have helpers who are less knowledgeable helping out and you ask a question which they do not know, they call over someone who can answer it. This store specializes in reef tanks even though they do sell some freshwater specialty items and reptiles and amphibians.
In-Store Display Tank
Most good pet stores that carry reef supplies will maintain a display reef tank of their own. The long term health of their own tank(s) gives you a direct correlation on how well they really understand reef keeping. The key words here are ‘long term health’. Frequently a poor quality pet store that has difficulty in maintaining their own tank, will tear it down every few months and then set it back up to keep it looking OK. You might see it soon after setup and make the false assumption that they know what they are doing. Monitor the tank over the next few months and see if the specimens are thriving and algae is kept under control.
Another thing to watch for is a display tank in which the specimens are for sale. This tank may look OK, but since the specimens are constantly being rotated in and out of the tank, you cannot tell if they are thriving or merely surviving until someone hopefully takes them home before they die. These tanks are often seriously under lighted which prevents algae blooms, but which also would prevent many of the specimens from surviving long term.
If a pet store does not have a nice display tank, it does not mean you should not necessarily do business with them at some level, but it does mean that you should regard any suggestions on how to maintain a reef tank suspect. After all, if they can’t or choose not to keep a high quality reef tank themselves, how can you have any confidence that they are talking from experience rather than from something they read in a book. Worse yet, they may be telling you something only to sell whatever product they have sitting on their shelves and unfortunately, there are a lot of expensive snake oils being sold in this hobby to the unsuspecting hobbyist.
Observe the specimen tanks
A quality pet store takes pride in their specimen tanks as well as their display tanks. There should not be a lot of dead or dying fish in the tanks. Some mortality is to be expected since the animals are always subjected to considerable stress during shipment to the store, but it should not be excessive or due to obvious disease symptoms. Corals, clams and other light requiring specimens should be under adequate lighting to maintain them in good health. Typical specimen tanks are fairly narrow and shallow and 2 VHO type fluorescent lamps running the length of the tanks is usually the minimum lighting needed for long term health of the specimens. High light requiring specimens such as SPS corals and Tridacna clams should only be kept under Metal Halide or large amounts of VHO/PC type lighting.
LFS or Mail order?
The term LFS is short for ‘Local Fish Store’. This is your local pet store that carries at least some reef tank supplies. If a quality LFS exists in your area, it is the preferred way to buy your specimens. You can observe them prior to purchase for health and color.
A version of LFS are the large retail chain stores such as Petco. These stores seldom have reef knowledgeable personnel on staff, although there are some exceptions. Their livestock typically is inferior health wise from the smaller LFS. While it is OK to purchase livestock through them if it is healthy, I would not recommend depending on getting any significant useful advice.
Mail order is becoming more and more popular in this hobby for purchasing both supplies and livestock. It has several advantages. One is that dry goods i.e. non-livestock items, are generally considerably cheaper than at the LFS. Also, they may have a better selection of livestock than you are able to find locally. As an example, a popular power head sells at the LFS here for about $45. I can purchase the same one mail order for $18. One thing to be cautious of is that mail order items may also have shipping charges applied. This can add significantly to the cost of the goods, especially for livestock that require next day priority delivery service from UPS or FedEx. Dry goods orders are generally fairly cheap to ship. When purchasing livestock, you obviously are not going to be able to see the exact item that you are purchasing, so you are more at the mercy of the company you are buying from. I have provided some links in the links section of on-line suppliers that I have first hand knowledge of as being good businesses to do business with. I have also listed some that have been less than stellar performers when I have dealt with them.
My rule of thumb is the following:
If a good quality LFS exists in your area, try to buy as much as you can through them. Remember that this is a hobby for you, but it is their livelihood and the more they sell, the better they will be able to stock their store. Good advice is invaluable, as is being able to hand select your specimens. Use mail order for specimens that you cannot easily get locally or when significant cost savings can be obtained on dry goods, especially items that you purchase over and over such as supplements.
Tank Selection
Selection of your tank can be one of the most important and expensive decisions that you will make in this hobby.
Tank Material:
Reef tanks are constructed of either acrylic or glass. Each type of tank has advantages and disadvantages which are listed below:
Acrylic vs. glass
Pros
Very light weight. Easier to move when empty which can be important for large tanks and the final installation will be slightly lighter.
Acrylic is more transparent than glass. Large glass tanks tend to have a greenish tint to the glass unless special very expensive iron free glass is used for the front pane. This is sometimes called Sapphire glass.
Acrylic is a better thermal barrier than glass.
Acrylic is less likely to shatter catastrophically if it takes a hard blow.
Acrylic has no glued seams that may fail over time.
Acrylic is easier to drill for plumbing hookups
Cons
#1 problem is that acrylic can be easily scratched when cleaning the inside of the tank. All acrylic tanks will get covered with small scratches over time. This are not too noticeable as long as you avoid accidentally getting a piece of sand or coralline algae between the cleaning device you are using and the acrylic which can cause large scratches.
Costs differences between the two depend largely on the size of the tank. Small tanks are always cheaper when using glass. As the tank size increases, the cost advantage starts to swing toward the acrylic tanks. Typically this occurs if you go above a 180 gallon tank size which is the largest standard glass tank.
Tank Size
This is a major decision point when setting up a reef tank that will dictate many of your future decisions. The conventional wisdom for reef tanks is the bigger the better. Unfortunately, the bigger the tank, the more expensive it is to setup and
the more expensive mistakes tend to be. One the other hand, if you go too small, you will quickly outgrow the tank and it can be a little more touchy to keep consistent water parameters due to its small water volume.
Here are my recommendations:
For someone who wants to get into the hobby in a small way either due to finances or not yet sure if this is what you want to do with your spare time, a 29gal tank is a good size. It is big enough to house a reasonable array of specimens, and is fairly easy to light because it can use 24" long fluorescent tubes or a single metal halide bulb. It is also tall enough to give some vertical feel to the reef. A tank of this size is usually made of glass and an inexpensive external overflow can be used to connect to a sump below the tanks. When starting with this size of reef, you should be prepared to upgrade if the reef bug really bites you. Tanks smaller than a 29 can be used, but they start to limit what you can do with them. A 20 gallon long for instance does not give you enough height to build a decent reef structure, but it would be OK for a lagoon type setup.
A moderate size tank that works well is in the 70 gallon range. This size of tank usually has a width of 18" which allows for good aquascaping of the reef. It is large enough to build a decent long term reef that you will not quickly outgrow unless the reef bug bites hard.. The common 55 gallon size works OK, but it is only 13" wide which does not allow for as nice of a reef structure to be built.
Moving up a notch, the 120 gallon size tank is a very nice size for a reef. It is 4’ long x 2’ x 2’. The two foot width allows for great aquascaping and the two foot height allows for a nice tall reef structure while still being manageable to get ones hands down to the bottom of the tank to do maintenance or arrange corals. Being four foot long, it is generally easier to find a spot to put it than with a longer tank. It is also at the upper end of what 2 MH lamps or 4’ fluorescent lamps will adequately light. It is also at the point in tank sizes just before you have to start giving serious consideration to floor loading. A 120 gallon tank will weigh in excess of 1000lbs.
Moving up from here, there are some guidelines to keep in mind.
One approach is to keep a two foot height and width and extend the length out. Up to 8 feet is common. Once you go past that length, the price tends to go up rapidly.
If the budget allows, a wider tank is almost always better than a narrow tank. 30" width is a great size and some people go 36"-48" or wider if space and budget allow for it.
Taller tanks tend to look nice, but consideration has to be given to how you will service the tank. Once you can no longer reach the bottom, this suddenly becomes difficult. If you are planning on using a DSB (Deep Sand Bed), which is typically 6" or so deep, this will take up that amount of tank depth and you may want to go with a deeper tank than you normally would to compensate. Another thing to bear in mind is that the higher the tank, the thicker the glass or acrylic needs to be and hence the more expensive the tank will get.
Taller tanks require higher intensity lights to provide adequate lighting to the bottom of the tanks. One general rule of thumb is that 175W MH lighting may be adequate for an 18" deep tank. A 24" deep tank my require 250W MH to achieve the same light penetration and a 30" deep tank may require 400W MH lamps.
If you are contemplating an unusual shape, such as a hex or corner tank, keep in mind that the lighting may be more difficult. Typically MH is the only lighting option, because fluorescent bulbs will not fit over the tank.
Another point to keep in mind when selecting a tank is to maximize the ratio of water surface area to tank volume as much as possible. This is usually a cosmetic tradeoff. The more surface area, the better the gaseous exchange between the water and air will be. Tanks will large sumps and protein skimmers are less of an issue in this regard since these items aid greatly in the air/water exchange process.
Lighting
Most of the specimens kept in a reef tank, other than fish or mobile invertebrates, are photosynthetic. That is, they receive part or all of their nutritional requirements from the lighting that they receive. This is accomplished by the fact that they have symbiotic algae which lives within the tissues of their bodies. The algae utilize the light for photosynthesis and the coral benefits from the byproducts of this process. If insufficient lighting is provided, the algae will die or slow down their activities and these animals will slowly starve to death. Also, some of the colors of photosynthetic corals and clams are attributed to the symbiotic algae and the coloration a specimen will often increase under higher intensity lighting.
Lighting is probably the biggest decision in setting up a reef tank. You can skimp on virtually everything else, but not this one unless you are willing to limit the inhabitants of your reef to those which can tolerate the lower quality light that you can provide. Like the size of your tank, your budget may determine for you the quality of light that you can give your reef. You cannot just walk into a pet store and buy that nice looking aquarium and expect the fluorescent hood that comes with it to work for your reef tank because it won’t.
Lighting has two important characteristics that you must consider, intensity and color. Intensity is the brightness of the light and relates to how much energy the lighting is putting into the tank environment. Color of the light is also important as the photosynthetic processes that are occurring in the tank are targeted to work optimally with the color of the light normally available on the reef.
Lighting Intensity
Intensity of the light relates to how much light energy is present at the surface of the water. There are a number of ways of calculating the amount of light you have or need in your tank, which are described below.
One of the more popular units of measure being used in literature now is the PAR (Photosynthetically Available Radiation). PAR relates to the amount of energy provided in the spectrum that is useful for photosynthesis. Unfortunately, there is no easy way for the hobbyist to directly measure PAR. This rating is most commonly used to compare the efficiency of one lamp to another.
The best way to actually measure the amount of light is to use a light meter made for this purpose. This type of meter measures lighting intensity in a unit of measure called Lux. A light meter will cost around $100 dollars. In general, the goal is to achieve a minimum of approximately 25,000 Lux at the surface of the water if keeping SPS corals with 20,000 to 40,000 being typical. Lower light tanks can get away with less. Measuring the light intensity using a light meter gives a completely accurate indication of how much light is really reaching your tank, however it is not really necessary.
One way to ballpark your lighting requirement is to use a watts-per-gallon calculation. This method is not as popular as it use to be since it does not take some variables into consideration such as tank depth or the efficiency of the light source, but it is still useful. You obtain this number by dividing the watts of lighting in your light fixture by the gallons of capacity in your tank. For a high light intensity tank, you should use a figure of 8-10 watts/gallon as your basic target. A lower light tank can get by with approximately 3-6 watts/gallon.. How does this compare with the typical lighting supplied by a tank manufacturer? As an example, a 55 gallon tank with one 4-foot long 40 watt fluorescent light which is a typical store bought configuration would have a watts per gallon of 40W x 1 bulbs = 40W total / 55 gallons = 0.75 watts per gallon! Now consider that you should aim for approximately 8 watts per gallon in your reef tank. For this 55 gallon tank, you would need about 55 gallon x 8 watts/gallon = 440W! That is about 11 times the amount of light provided by the store bought hood! Since it is physically impossible to put 11 40watt tubes above a 55 gal tank, it should be obvious that we need to find more efficient lighting schemes for our tank. If a low light tank is the target, you can see that the absolute minimum to achieve 3 watts/gallon would be 40W x 4 bulbs = 160W total / 55 gal = approximately 3 watts per gallon.
A better approach, especially when dealing with Metal Halide lamps is to size the lamps by the depth of the tank and determine the number of lamps by the square footage of the tank surface.
175W MH is suitable for up to 18” deep tank
250W MH for 18” to 24” deep
400W MH for anything deeper than about 24”
These are ballpark estimates only for a moderate intensity tank. High intensity lighting might make use of 400 watt MH on tanks as shallow as 18".
The other factor is the number of lights and the rule of thumb is that a MH lamp will illuminate approximately a 2’ x 2’ area of the tank. A 4-foot long tank would require 2 MH lamps. This is true whether the tank is 18” wide or 24” wide. A 6 foot long tank would require 3 lamps and an 8 foot long tank would require 4 lamps. If the tank is a more square configuration, the same basic rules apply. A 5-foot long tank that is 36 wide has 15 sq./ft. of surface area. Since each lamp can cover approximately 4 sq./ft., 4 lamps would be the appropriate number to use.
Other major factors that affect the intensity of the light are:
The distance of the light from the surface of the water. The light drops off by the square root of the distance. Lights 4" above the water provide significantly more light into the water than lights 16" above the water. The only things that prevent the lights from being mounted with minimal spacing is heat buildup in the water, possible damage to the lights from water splashes and possible damage to the tank itself if it is made of acrylic or if it has a plastic brace near the lighting that can be damaged from the heat. Oh, and possible damage to your arm when you try to service the tank.
Depth of the water has a significant affect. In any given tank, the lighting will be brightest at the surface of the water and decrease with depth.
Coloration of the water due to dissolved organics can block considerable amounts of light.
A good quality reflector which directs light otherwise lost in the canopy back to the water surface can have a significant affect on the amount of light entering the tank.
Any surface between the light and the water surface will reduce the light intensity, especially if dirt, algae or salt covered.
Lighting Color
The color of the lighting must simulate the sun at some depth in the ocean. Sunlight in shallow water has not been affected much, but as the water deepens, the red and yellows of the light are absorbed while the blues and violet colors stay relatively strong. At 15 feet down on a reef, the light is tinted slightly blue. At 50 feet, the light is strongly blue and the overall intensity is lower.
Color of lighting is typically referred to using the Degrees Kelvin scale. The lower the degrees Kelvin, the more yellow/red the color will be. This is also referred to as a low color temperature. The higher the degrees Kelvin, the bluer the color will be and is referred to as a high color temperature.
We can relate this to our tank in the following manner. The lower color temperature lights simulate a shallow reef, while a higher color temperature light simulates a reef in deeper water. Lighting on the market typically starts out at about 5500 K. There are even some being sold that have a 4300 K color temperature. These have more yellow caste to them most people prefer. I recommend that a minimum of a 6500 K light be used to simulate a shallow reef. These are often supplemented with blue lights called Actinic lights to give a slightly higher color temperature (bluer color). These actinic lights are also useful for simulating low light sunrise and sunset conditions in your reef. Other lights have a rating of 10,000 K which give a crisp, bluish/white light which simulates a depth of about 15 feet. There are other lights that have a rating of 12,000 to 20,000 K which give a deeper blue light which simulates a fairly deep reef.
In general, there is a tradeoff between the color temperature of the lamp and the intensity of the light it produces. The rule is, the higher the color temperature of the lamp, the lower the intensity of its light output. A 250W 6500K lamp will tend to have more light intensity than a 250W 10K lamp for instance. 10K lamps are the optimal compromise between the look and intensity for many reef tanks. 12K and above are gaining popularity, but frequently have a strong enough blue tint to them that some people do not like them. The intensity is also pretty low.
Another consideration when choosing a metal halide bulb is the CRI (Color Rendition Index) The CRI index relates to how well the light reproduces the true colors of an object. This number ranges from 0-100 with the natural sunlight registering 100. Artificial lighting rarely exceeds 95 and is often lower. Most 10K lamps have a CRI of around 95 and thus do a better job of reproducing the true colors of the coral and other specimens than most other lighting.
Types of lighting useful for a reef tank fall into three primary categories, fluorescent, power compact and Metal Halide.
Fluorescent Lights
Fluorescent lighting is the choice of many. While it is possible to be moderately successful with normal out (NO) lamps such as you buy at Home Depot, it is not possible to build more than a low light tank with these, even if the entire surface of the tank is covered with bulbs. A much better choice is to use VHO (Very High Output) bulbs. These VHO bulbs must be run on a special VHO ballast, but they provide about 3 times the light intensity of the NO bulbs
.Typical lamp wattages are shown below:
Length of lamp
Normal VHO
18" 15W
24" 20W 75W
36" 30W 95W
48" 40W 110W
60" 140W
72" 160W
96"
Let’s use our 55 gal tank as an example. Two 4-ft VHO lamps put out 220W which gives us about 4 watts/gal. This is sufficient for a low light tank. Four 4-ft VHO lamps put out 440W and gives us about 8 watts/gal which is enough for a high light tank. Four NO bulbs over the same tank will provide about 160W or 3 watts/gal which is a marginal level even for a low light tank.
Actinic bulbs which have a strong blue color are almost always mixed with daylight bulbs in VHO setups in about a 50-50 mix.
Power Compact Lights
PC lights are really just another form of fluorescent light. The bulb is essentially a skinny fluorescent tube that has been bent into a U-shape with both connections on one end of the bulb. They tend to have a higher light output for the same wattage of bulb than the equivalent VHO bulb. PC lights are also available in small sizes making them a good choice for very small tanks. Common wattages available include 9W, 13W, 55W and 96W.
Some of the PC bulbs on the market have had poor reliability, perhaps because they are supported on only one end.
The new incandescent bulb replacement tubes at the local Home Dept are forms of PC. Their color is pretty yellow, but they have some use for growing macro algae or non-cosmetic lighting of tanks.
Metal Halide Lights
Metal halide (MH) lights are the big guns in the world of reef keeping. Optimum lighting conditions for a high light reef is best achieved with MH lighting, especially if the reef is to be an SPS/Clam tank. MH lighting comes in many sizes from 70W to 400W and even higher. They are small compared to fluorescent lights and allow for a higher density of lighting over the reef. They are a pinpoint source of light, which gives them better punch (penetration) in deeper tanks. Being a pinpoint source of light also means that they simulate the effect of water ripple shadows similar to a natural reef, which most people find very enjoyable. Metal Halide is generally the optimum way to light a reef tank although you can frequently get away with less intense lighting systems depending on the livestock which are kept.
MH Types
There are primarily 3 types of MH lighting. Single-ended MH bulbs, Double-ended MH bulbs (HQI) and Mercury Vapor (MV). MV is technically not the same technology as MH, but some of the newer bulbs such as the Iwasaki’s have performance levels which put them into the same ballpark as normal MH.
Single-Ended MH
These are the most common MH lighting available. They use a large light bulb looking socket which they screw into called a Mogul socket. These bulbs come with an outer glass envelope which blocks the large amounts of UV radiation that these bulbs
produce.
Double-Ended MH
HQI lamps require a double-ended socket for mounting. These bulbs do not have UV shielding and this needs to be provided as part of their mounting, otherwise the UV can burn the corals. These lamps tend to have some of the best color and efficiency performance, but also tend to be a little more trouble to deal with.
Mercury Vapor
Mercury Vapor lamps are usually a very yellowish color. There is now a version made by Iwasaki that produces a fairly good white color. It is rated at 6500K color temperature, but seem to be very variable with some bulbs appearing very yellow and some being a very nice white. These bulbs are becoming fairly popular since they put out a higher level of PAR relative to normal MH. Some people find the color a little too yellow, but this can be minimized by supplementing with Actinic blue lighting. These bulbs tend to be cheaper as well.
Most MH installations also include Actinic fluorescent lamps as well in order to provide dawn and dusk lighting conditions.
Metal Halide Ballasts
Metal halide lamps require a ballast to drive them. The ballast provides the high voltage needed to ignite the lamp and the drive voltage required to keep the lamp running. The ballast is remotely mounted from the lamps due to weight and heating concerns. There are two primary types of ballasts available. One is called a TAR ballast. These are low tech, heavy, large, low efficiency, low cost, but reliable devices and then there are Electronic ballasts that are high tech, relatively light and small, higher efficiency, higher cost and sometimes failure prone. The ballast you chose will be determined by the type of lamp you are planning to run (Single-ended, HQI or MV) and whether you prefer the low tech (TAR) or high tech (electronic) approach to ballast construction.
A popular TAR ballast on the market is the PFO ballast. It has the benefit that you can get two ballasts in one housing, which is convenient (but bulky and heavy). Advance is another common TAR ballast.
Popular electronic ballasts include Ice Cap, E-Ballast and Sun Seeker.
Lighting Costs
Lighting costs can vary widely depending on how much work you are willing to do yourself and where you buy the parts. Prices below are ballpark MO pricing.
For our hypothetical 55 gal tanks, a four bulb VHO lamp system will cost approximately $175 for the ballast, $100 or so for four bulbs, $50 for holders and electrical connectors and some more money for reflectors. PC lighting cost would be similar.
For an equivalent MH lighting system, I would chose a dual 175W ballast ($175), two 175 10K lamps ($200) and reflectors ($60). The metal halide system will tend to be a little more expensive. Note that the wattage of the two 175W MH lamps is 350 watts total. This seems like less than the 440W VHO, but MH is a more efficient technology than VHO and you will actually get more usable light from the MH.
Lighting Related Heat Concerns
Lighting systems can sometimes generate enough heat to cause excessive temperatures in your tank. The more wattage of light you have over your tank, the more heat it is producing. A misperception about MH lighting is that it generates more heat than fluorescents. Actually, MH lighting is more efficient and hence generates less heat for the equivalent light output. Since this heat is concentrated in a small area instead of over a long bulb, the MH bulb itself does get hotter and can be a serious burn hazard if contacted.
Heating from the lighting system can be managed via fans in the hood which cool blow air across the water surface and other fans which extract the hot air out of the hood. You do not want to blow the air directly at the lamps as that is now what you are trying to cool and excessively cooling MH lighting can shorten its lifespan and decrease its light output. In worse case scenarios, an external water chiller may be required to keep tank temperatures down.
Filtration
Hobbyists moving to reef tanks from the freshwater or even saltwater fish only tanks are frequently puzzled over the apparent lack of massive power filters that they are familiar with in the other hobbies. Reef tanks require a degree of finesse rather than sheer brute force when it comes to filtration. Whereas the other hobbies typically are trying to achieve crystal clear water via removal of all particulate matter and rely upon water changes to dilute pollution, reef tanks are trying to achieve crystal CLEAN water through removal of all pollutants at a level that water changes alone could not accomplish.
What does this mean? In simple terms:
The hobbyists wants to remove as much biological waste from the water as possible before it enters the nitrogen cycle.
What waste does enter the nitrogen cycle gets processed quickly and completely from Ammonia to Nitrite to Nitrate and finally to harmless gases that can escape into the atmosphere.
There are a number of ways to try to achieve this goal which are outlined below.
Wet / Dry Filter
Old school was that a filtration device called a wet / dry filter was necessary for success with reef tanks. In fact, there are many still being sold today. Wet/dry filters are large acrylic or grass filters that become the sump for the tank and include a tower area in which return water from the tank is trickled or sprayed over a plastic media. The logic was that oxygen loving bacteria would colonize the media and convert the waste products generated by the tank into relatively harmless nitrates. This was the 'dry' portion of the filter. The 'wet' portion typically included a sponge for mechanical filtration and space for heater, carbon and possibly a protein skimmer. They in fact accomplished this mission, but have several important downsides. Tanks with wet/dry filters frequently have problems with nitrates continually increasing, only to have the nitrates drop to zero when the wet/dry filter is removed. Why this might be, is not fully understood, but it is a well established phenomenon. The conversion of wastes to nitrates is accomplished efficiently, but the final step to convert it to harmless gases is not and therefore the nitrates accumulate in the system. Also, the mechanical filtration that is sometimes employed in wet/dry filters is counter productive. Reef tanks house countless organisms whose lives depend on filtering the water. Mechanical filtration is redundant and counterproductive in the long-term.
Long story short, do not spend money on a wet/dry filter. If you already have one and are having problems with nitrate accumulation, slowly remove the biomedia until the unit serves as simply a sump.
Protein Skimmer
The first step in clean water is removal of pollutants before they enter the nitrogen cycle. Mechanical filtration of visible particulate matter in the water may seem like the best way to achieve this, but it is not. Much of the visible matter is harmless flocculent while the harmful stuff is invisibly dissolved in the water column. This is where protein skimming comes into play.
A protein skimmer operates on the principal that protein and other organic wastes tend to collect at the water surface due to the affinity to having half their molecule in the air and half in the water. This is why scum forms on the water surface. A bubble floating in the water tends to collect these wastes for the same reason.
A protein skimmer consists of a reaction chamber through which tank water is mixed with fine air bubbles. These bubbles collect the wastes onto their surface through natural processes as the bubbles rise through the chamber. The bubbles collect and carry the waste products up toward to the top of the reaction chamber. As these waste products rise in the chamber, a foam is created which is eventually pushed up through a tube and into a collection vessel. These organic wastes are mostly fish wastes and the protein skimmer does a good job of removing them before they have to go through the biological breakdown cycle. A person only has to see and smell the output from the protein skimmer to realize how much gunk these things do remove from the water.
Protein skimmers are constructed in several different ways.
Originally, skimmers were constructed of a tall acrylic tube with a wooden air stone in the bottom. Wood was used to provide the fine air bubbles necessary to make the skimmer work properly. The water was forced to travel down the tube while the air bubbles were trying to rise up through the water. These skimmers worked well and are still in use in small quantities today. Their downside is primarily the need to occasionally replace the airstone and the need for a fairly high pressure air pump.
Most skimmers sold today are called venturi skimmers. These skimmers remove the need for the air stone and air pump by creating the bubbles through a venturi effect. Water is forced via a water pump under pressure through a restriction which has a small air hole in it called a venturi valve. The restriction causes a vacuum to be created and air is sucked in through the small hole and mixes with the water. Venturi skimmers can create a more turbulent water column than airstone based skimmers and do not require as tall a reaction chamber to achieve the same affect and therefore can be easier to fit under the tank stand.
Protein skimmers have been in the hobby for quite some time and have proven their value in almost all situations. It is highly recommended that protein skimming be provided on any reef. Although it is possible to setup a reef tank with a skimmer, there is no downside to providing one unless you are trying to setup a tank which houses specimens from more turbid waters, such as Goniopora which might benefit from increased nutrient levels in the water.
Protein skimmers can either be purchased as in-sump models or hang-on-tank (HOT) models. In-sump models are generally more powerful and should be used if a sump is used on the tank. If no sump is used, then a HOT is the only other option. Some of these hang on models are ineffective enough to make them mostly worthless unfortunately.
Protein skimmers also have the incidental, but very valuable side benefit of providing a high degree of gas exchange and oxygenation of the water.
Algae Filtration
A method of filtration that has found favor with those who prefer the natural approach. The logic behind this approach is that algae will consume nitrates and other water pollutants as they grow and subsequent frequent pruning of the algae will export those nutrients outside of the tank. The algae employed is usually one or more of the Caulerpa species, although any algae, including hair algae, will perform the same function. Unless the tank is a lagoon tank, the algae is normally grown outside the main display tank either in the sump or a refugium if one is used. Simply adding a small light over the sump and and throwing some Caulerpa in gets this process started.
Downside to this method includes the fact that Caulerpa algae can go sexual and disintegrate almost overnight, dumping a heavy biological load back into the system. Frequent pruning seems to help minimize the chance of this occurrence. Algae growth can also leach chemicals back into the water that tend to yellow the water. Carbon can be used to minimize this problem.
Deep Sand Beds
Sand beds with medium to find grain particles that are over about 1" in depth create oxygen poor conditions in their deeper layers that are conducive to growing the type of bacteria needed to convert nitrates to harmless gases. DSB's take this strategy to extremes through the use of sand beds that are generally 4" to 6" in depth. At this point, they enter the realm of intentional (vs. incidental) filters and so are included here. Old school is that deep substrates will allow noxious gases, like hydrogen sulfide, to form in the anaerobic areas that can cause problems in the tank. Current thinking is that this is not a major concern and that this setup closely approximates what occurs in the substrate in the ocean. DSB's, and for that matter any substrate, should not be disturbed more than necessary. At one point, vacuuming the substrate was a common practice to keep it clean. Current thinking is that the sand bed should not be disturbed more than necessary to allow it to create and maintain the anaerobic regions. The sand bed also becomes populated with worms and other organisms that further help to recycle wastes within the tank.
The downside to this method is primarily that the DSB can consume large amounts of the tank vertical depth and be somewhat unsightly where it is in view along the front glass of the tank. For this reason, some DSBs are being setup in sumps where it's work can be done out of view of the main display tank.
Carbon
Carbon is frequently employed in reef tanks as an adjunct to other filtration methods. Carbon can be from a natural mined source similar to coal, or can be produced through extremely high temperature processing of coconut shells or similar. Carbon absorbs compounds in the water that can discolor the water improving the look and light penetration. It can also absorb other compounds that might be otherwise harmful to the tank. Some reef keepers are concerned that it might also remove useful components as well, but the benefits seem to outweigh any likely negatives. Carbon is recommended to be used continually in small quantities. For instance, a quantity of about 1/2 cup for a 55 gallon tank would be appropriate. The carbon should be replaced about once a month to keep it effective. Some people only use GAC a few days a month to minimize it absorption of any good compounds, but the sudden change in water clarity and composition this method imposes on the tank does not make much sense and is counter to the goal of maximizing water stability within the reef environment.
When using carbon, it is very important to chose a high grade version which is typically called GAC (Granulated Activated Carbon). GAC is fairly soft and has small rice grain particle sizes that increase absorption rate. High quality versions also minimize any phosphates or other contaminates that they might otherwise contain since they are organic in nature. The small grains of GAC require that it be contained in a mesh bag or similar to prevent the particles from migrating around. It is also important to not put loose GAC in direct water flow as there is evidence that tumbling GAC can create small carbon particles that enter the tank and can be somewhat detrimental to the tank inhabitants. If used in a high water flow area, ensure the GAC is tightly packed to prevent its movement, otherwise a quieter part of the sump where the water can circulate gently around the GAC is the best place to locate it.
The carbon typically sold in LFS for freshwater use that is very hard and has very large particle size should not be used in reef tanks. They are fairly ineffectual and may have unwanted contaminates.
Here is an example of a typical high quality GAC
Other Contraptions
Hang-on style power filters have little value in a reef tank and should generally not be used, although on a small tank an outside power filter can sometimes be used to house a small heater and carbon outside the tank and provide water flow in the tank. In that case, the filter portion of the outside filter is left unused. There are some outside filters which are designed specifically for reef tanks that include a small protein skimmer and these are generally ineffectual enough to be mostly useless.
Under tank power filters are also generally not used, although they sometimes are used for holding GAC, or other filter media that might be used on occasion.
UV sterilizers were quite popular for a while and are still used by some hobbyists. They work on the principal that a stream of water is passed through an enclosed tube and over a intense UV light source which kills any organisms that it comes into contact with, effectively sterilizing the water. The value is dubious at best although a case may be made for it when the water has parasites or similar that need to be dealt with.
Utilizing ozone to sterilize water was popular at one time, but is little used today. Ozone is a gas which is formed in the presence of an electrical field and has a very noticeable odor to it. The smell associated with lighting or other electrical arcs is ozone. Ozone, unlike UV, it is not limited to a small reaction chamber and has far reaching side affects. Ozone is a strong oxidant and it can easily damage delicate membranes such as fish gills.
Current reef keeping theory is that a healthy tank automatically helps to fight bad organisms in the water and such preventative measures such as UV sterilizers and ozone are unnecessary and potentially bad. Unlike fish only tanks that seem to frequently have massive fish infections from parasites and bacteria which must be controlled via medication or mechanical means, reef tanks that are in good health rarely have significant disease problems.
Substrates
Substrate is the sand or gravel that covers the bottom of the tank. Substrate can be cosmetic, a place for critters to burrow and dig through and it can also be an important adjunct to the biological ecosystem within the reef tank. Old school was that a bare bottom tank was important so that all detritus could easily be removed. That is no longer true and you will not find many bare bottom tanks around these days. Today, there are 4 main types of substrates in use:
a. 1" layer or so of coarse crushed coral gravel.
b. 1-2" of layer of smaller medium grain sized aragonite or coral sand
c. Plenum system – which consists of a stratified fairly deep sand bed over a open area (plenum).
d. DSB – Deep Sand Bed, which is a deep 4"-6" or deeper sand bed made up of a mix of coral sand sizes, mostly fairly fine.
Coarse Crushed Coral Gravel
The coarse coral gravel substrate is falling out of favor. The large particle size allows excessive amounts of food to fall into the crevices and this substrate does not provide a very good biological zone. Many tanks are setup with this substrate through lack of knowledge, but it should not be used even though this is sometimes the only substrate sold at the LFS. Coarse gravel CAN be used in the reef tank if it is used in combination with finer sand.
1.5"- 3" Medium Grain Substrate
The 1.5"- 3" deep, moderate particle size (1-2mm) coral or aragonite sand substrate is probably the most common and has been around for some time. Finer sand beds over about 1 1/2" start to have the ability to act as nitrate reduction areas. My tanks mainly rely on this type and there are many successful tanks constructed around this type of substrate. This setup also has the advantage that it does not consume excessive amounts of the tank depth like the following two options can. This is probably the easiest, safest and cheapest route to take. Of course reef keepers hardly ever take that route since there is always a better way of doing things right around the corner (or so we hope).
Plenum System
Plenum Systems – were made popular in the 90’s. They have a somewhat complicated construction in which a porus platform is constructed inside the tank that provides about 2" of water dead-space under the sand. The platform is covered with screen to prevent the sand from filling this void but allows water to pass through. The platform is then covered with successive layers of different sizes of sand to form approximately a 4" depth. The logic is that the dead water space provides a nutrient sink and will prevent nitrates from accumulating. This substrate type is starting to lose favor in the reefing hobby for several reasons. One is that it is complicated to setup correctly. Another is that there are many tanks using this system which do not seem to be performing any better than simpler systems and lastly, there have been reports that disturbing the sand bed has caused entire tanks to crash. I will not go into detail on this method since I believe it is a poor choice, but if you are interested in pursuing it, there is a monthly article in FAMA which can get you started.
Deep Sand Bed (DSB)
DSB's are the newest thing to hit the substrate scene. These consist of one more layers of fairly fine sand that is piled deeply in the bottom of the tank. In some ways, it is similar to a plenum system, but without the plenum and the sand depth is usually deeper. The only known downside to the DSB system is that it occupies a lot of the tank depth and can be somewhat unsightly when viewed from the front. The benefits are reputed to be many. The major one is that it’s depth encourages a wider range of biological processes to occur in the tank than you get with thinner sand beds. This mostly relates to the substrates ability to reduce nitrates to harmless compounds. There are no known long-term problems with DSB substrates yet, unlike plenums, but the technique is still fairly new. To minimize the cosmetic impact, some reef keepers are implementing DSB's in external tanks or sumps. Whether you should use a DSB is mostly dependent on what kind of reef keeper you are. If you want a fairly easy, nice cosmetic setup, I would recommend staying with option ‘b’ above. On the other hand, if you’re a tinkerer and want to be leading edge and you have the tank depth to accommodate it, then DSB is worth looking into. The article 'Muddy Waters' by Dr. Shimek in the Further Reading section below is excellent reading on this topic.
Live Sand
There is one last spin to the substrate question and that is the topic of 'Live Sand'. Live sand is sand that comes from the ocean presumably with all the varied sand dwelling organisms still in it. The idea is to use some amount of live sand to 'seed' the remaining substrate with sand dwelling organisms. In concept, live sand makes perfect sense to create a thriving sand bed with a myriad of organisms in it in the reef tank very quickly. Many current hobbyists swear by the value of live sand. I am somewhat doubtful as to exactly how much benefit there is to be gained by its addition for two basic reasons. First, any 'dead' substrate seems to quickly be populated by organisms from the live rock. Second, much of the live sand I have seen appears to be pretty sterile looking sand which is stored in conditions that would preclude much of the larger life forms from surviving. If you decide to go this route, make an effort to get as fresh of sand as possible to get the most value for your money.
Making Saltwater
Saltwater is a major component of the reef tank. Virtually all reef tanks use a dry salt mix to create the saltwater used in them. This is not concentrated salt from the ocean, but instead is a carefully formulated salt developed from scratch. For those who live in the tropics (I used to live in Hawaii), you can collect fresh saltwater, but you have to be careful to do this away from sources of pollution. Saltwater from cold water areas is generally unsuitable since they often contain a high zooplankton component that will rapidly deteriorate in the tropical temperatures of the reef tank. There is also the chance that salinity will vary widely if there is freshwater runoff near the collection site.
There are a number of brands of salt mix on the market to chose from. I have used several different ones including Tropic Marin, Instant Ocean, Corallife and Kent. Probably one of the best is also one of the cheapest (how often does that happen?) and that is Instant Ocean. It is easy to pick one of the higher priced, fancier looking brands, but it is not necessary. Analysis of the salt mixes that have been performed by others have shown that Instant Ocean (IO) as it is often referred to has as optimal a formulation as any of the other salts and is better than most. IO has a sister brand called Reef Crystals that is more expensive and has elevated levels of calcium when mixed. The added cost of this product does not make much sense since these levels can easily be adjusted using cheaper methods.
When mixing the saltwater, it is very important to use purified water. Most public and well water sources contain excessive amounts of chemicals, elements and compounds that can cause problems in the reef tank. Common undesirable additives that frequently come free with water include phosphates, nitrates and silicates, all of which can cause excessive algae growth. This becomes even more important for replacement water (water which must be replaced due to evaporation). Since the chemicals do not evaporate, they tend to get added with each water addition and accumulate in the system over time. So even if the basic water concentration of impurities is OK, they can still accumulate to levels that are not OK. Some people have found that they can use tap water as-is without problems, but
thxb4
