Aquarium Setup and Design


Tank dimensions are determined by the individuals inside your aquarium. Some fish require swimming space, and the length of the tank may be important. Some corals require intense light, and the height of the tank may be important. Some plants grow like bushes, and the width of the tank may be important. Also, the surface area of the bottom influences how much substrate and lighting you will need. Finally, the volume of the tank determines the flow rate through the circulation systems and filtration systems.


Choose lamps based upon the luminosity (lumens), the color (spectra), and power (watts). The best choice for your lighting will match the needs of any photosynthetic individuals’ spectra, provide the most luminosity, and consume the least power. Both fluorescent and metal halide lamps excite electrons bound to certain chemicals. When these electrons relax, the lamp emits light of distinct wavelengths. There are very few options for these chemicals. As a result, most lamps contain varying amounts of the same chemicals.

Fluorescent tubes emit light from the surface of a long cylinder. Avoid spirals or other strange shapes when purchasing a fluorescent lamp. Choose parabolic reflectors designed for lamps of your radius. Compact fluorescent lamps will never work as well as the equivalent straight tubes. Metal halide lamps emit light from a line source, which in turn excites a small cylinder to emit light. Because of this complexity, reflectors are designed for very specific metal halide lamps types. If possible, decide upon a particular lamp make and model and then choose the best reflector for that lamp.

All lamps are designed to operate at specific temperature. Achieving this may involve adding ventilation to your lighting or purchasing a chiller. If all else fails, you may try redirecting your HVAC to supply air, return air, or both.

As to date, the most efficient lighting available is german made T5 fluorescent lamps under parabolic reflectors. The spectra are also very impressive. American LED manufacturers have made leaps and bounds, with the introduction of new designs that come within 15% of the efficiency of T5 lamps in 2006. LEDs are rarely chosen because of high initial costs; however, long run costs of LED systems are significantly lower.

Metal halides are an attractive option for reef aquariums because they are almost a point source. If you disturb the water’s surface, then a metal halide will sparkle, similar to how sunlight appears on the bottom of a pool on a bright, windy day. Keep in mind that only the light from the metal halide will sparkle, and choose your color spectrum accordingly if you also will use fluorescent lamps.


Mechanical filters remove material from the water column by physically separating the material from the rest of the water. This separation allows easy removal of this material. There are several methods of mechanical filtration: sudden decreases in the linear velocity of water as the flow passes a drain, trapping the material in another, inert material, or foam fractionation (protein skimmer). Mechanical filters can easily be automated to minimize maintenance.

Chemical filters either selectively partition chemicals onto a surface or react with chemicals in the water column. Chemical filtration requires regular replacing or recharging of media.

Biological filtration is, in essence an integration of chemical and mechanical filtration via individuals within your aquarium, or connected to the aquarium through plumbing.

Protein skimmers are best suited for fish only tanks. Natural reefs rely on tiny particles and individuals to increase biomass. Protein skimmers are extremely efficient at removing tiny particles from the water column. As such, protein skimmers often starve a reef aquarium.

UV sterilizers are work horses in many setups. They really belong under lighting, but are considered filters by most. UV sterilizers destroy some of the nucleic acids that pass through. If enough nucleic acids are destroyed, then the individual cannot reproduce and is sterile. Use UV sterilizers with care, as they can do more harm than good.

Circulation and Aeration

The water in the aquarium can be thought of as two systems: the bulk and the surface. Water circulation is best accomplished with external pumps. Placing electric motors inside the water column also places electric fields inside the water column, which can distress a large number of individuals.

To achieve similar water quality throughout the aquarium requires proper circulation. Not only is volumetric flow (GPH, LPH) important, but the linear velocity (mph, m/s) of flow is also important. The velocity of water determines what reaches your filter in the first place, and individuals within the aquarium experience linear velocity, not volumetric flow. Choose pumps on the inside diameter of the suction and pressure side, the power (watts), and the volumetric flow (GPH). Be careful, different manufacturers may report their numbers in different units or at different head heights. I’ve found that each manufacturer has several basic designs that they scale their models from. From each line, a single model will perform most efficiently. Rarely will each model in a line outperform all models in a competing line.

Reef aquariums often require pulse flow. Placing a mechanical device in line can change the direction and/or intensity of circulation. Programmable devices can fine tune the on/off cycles to your liking, but ensure you purchase a pump that is designed for frequent stopping and starting.

The surface provides gas exchange with the surroundings. If the surface of the water is not turned over, then undesirable individuals may grow thin colonies on the surface of the water. These colonies may inhibit gas exchange and block lighting to the rest of the aquarium. Make sure you have something that only filters the surface of the water called an overflow.

Aeration may be achieved entirely with good air flow over a clean surface of water. If photosynthesis increases the partial pressure of oxygen above that of the surroundings, then aeration may not be required. In such cases, separating the aquarium from the surrounding air may improve the water quality.


An unsealed aquarium exchanges all gases including water with the surroundings. Individuals in the water and owner dosing impart a concentration gradient upon a number of chemicals within the water. Blowing or sucking air across the surface of the water will decrease this concentration gradient. Increased evaporation will also cool water.

Ventilation offers an economic opportunity to dose an aquarium. Evaporation removes only water, but leaves the dissolved chemicals behind The evaporated water can be replaced by water high in nutrients for plants or a reef. By increasing the evaporation rate, the maximum rate of dosing is also increased.


The substrate at the bottom of the aquarium can serve many purpose other than aesthetics. In planted aquariums, the substrate provides rooted plants with chemicals not available to individuals in the water column. If you have an undergravel filter, then the substrate doubles as a filter media. If you do not have an undergravel filter, then the electrochemistry of ion exchange changes dramatically with deeper substrates. Because of this, many chemical reactions take place which would not take place if water circulated through the substrate. For example, iron uptake by plant roots becomes easier, but so does the production of methane. In a reef aquarium, the substrate may become a host to a variety of individuals and acts as biological filtration. Similarly, care must be taken in a reef aquarium as deep sand beds have very low reduction-oxidation potentials. Very scary chemistry can build up and release all at once.

The Elements

Oxygen is the most important molecule in water. Proper aeration, photosynthetic individuals, compressed gas, or ozone generators may be employed to elevate oxygen levels. The last two methods can overdose with oxygen or ozone and elevate the reduction-oxidation potential too much, essentially rusting individuals in your tank. Ensure that if a control system fails then the maximum dosage rate will not be toxic.

Carbon comes in many forms. Plants need carbon to thrive. The simplest type of carbon added to aquariums is carbon dioxide. Many people buy pressurized CO2 in cylinders, culture yeast to ferment, or make it electrochemically, then plumb this to the circulation system. A few plants actually use bicarbonate instead of carbonic acid, which means you can actually fertilize with baking soda. Another option is to overstock the tank with fish, who will provide an abundance of CO2. This option requires a hefty filter and more frequent water changes. Reef aquariums often use carbon dioxide to elevate calcium levels in reactors. This addition must be offset to avoid low pH, and magnesium sulfate is an attractive option. Elevated carbonate concentration (with calcium) in a reef allows individuals to precipitate calcium carbonate, a necessity of many individuals. Adequate turnover of the water, ventilation, protein skimming, and surface disturbances decrease the difference between carbon dioxide pressure in the air and in the water.

Nitrogen is essential for every aquarium. Ultimately, nitrogen is important to make proteins, nucleic acids, and other biomolecules. The source may be an amino acid or a nitrogenous base, but more than likely it is either reduced or oxidized nitrogen. Common reduced nitrogen compounds are ammonia, ammonium, and urea. Reduced nitrogen should be kept at low levels. Oxidized nitrogen is commonly referred to nitrites and nitrates, but most test kits fortunately measure other chemicals as well. Nitrogen should be present in your aquarium’s water in at least one form. Potassium nitrate is an extremely economic option. Biological filters, quality protein skimmers, and chemical absorbants are effective at removing nitrogen almost entirely from the water colony.

Calcium is important to all aquatic life. Quality plant fertilizers will ensure planted aquariums have plenty of calcium. For a reef aquarium, calcium is quickly consumed. Calcium reactors are effective at maintaining calcium in the water column, but pH must be offset as discussed under carbon. Calcium chloride does not affect pH, and chloride is reef safe. Saturating top off water with a mixture of calcium chloride and calcium carbonate should maintain both calcium and carbonate levels. Calcium salts can precipitate in the water column and test should be performed before adding calcium to the aquarium.

Potassium is the single most overlooked chemical in a planted aquarium. Plants must either take in new potassium of destroy old tissue to continue growing. There are no known negative issues with elevated potassium.

Iron is a tricky one. Iron may be the oldest chemical of life, and cells use iron to maintain the proper reduction-oxidation potential. Iron exists in two states in the aquarium: Fe(II) is missing two electrons and Fe(III) is missing three electrons. Fe(III) is not readily water soluble, so individuals must usually add an electron to Fe(III) before placing it into service. Adding electrons becomes easier as the reduction-oxidation potential decreases. For many planted aquariums, the substrate serves largely for cation exchange between the water and the plants’ roots to aid in iron metabolism. Anything from (perfume free) kitty litter to expensive substrates taylor made and color matched will work, depending on your standards of aesthetics. UV sterilizers quickly remove all iron from the water column.

Magnesium in water is depleted slowly by reefs and is essential to a reef’s growth. Buying a calcium additive with magnesium may be enough, or you can buy magnesium chloride which is readily soluble in water or magnesium sulfate.

Iodide and strontium are extremely important for most invertebrates, especially reef invertebrates. Typical levels are very low. Concentrations can be maintained by comprehensive additives or by buying plant cell culture tested compounds in bulk.

Phosphate biochemistry is extremely intricate. Phosphates are required for all life, but are typically limited in reef and marine aquariums to avoid algae growth. Planted aquariums require phosphorous, and its exclusion has become popular. However, phosphate buffers are frequently employed in growing aquatic plants on a large scale. Tap water usually requires enough phosphate for the planted aquarium, or you can dose with different salts depending on your tank’s pH. Chemical media, downforce protein skimmers, and biological filters remove phosphate.

Silicates are a favorite of diatoms. In either freshwater or saltwater, elevated silicates results in algae. Diatoms can extract silica from glass. Chemical media and downforce skimmers remove silica. Often, the same media removes phosphates

Chloride is extremely important to freshwater plants. Chloride is readily available in most water sources. Do not confuse with chloramine, which is also available in most water sources but is dangerous.


In general try to avoid taking material out of the aquarium. An excellent example would be to run foam fractionation (skimmer) on a sump, send the top fraction to a phytoplankton culture, have the phytoplankton overflow into a refugium, have the refugium empty into the display tank, which overflows into the sump. Each separate container would have its own lighting, substrate, and circulation. In this way, you really never have to add anything to the tank except water. The only cost is power, water, and lamps. Additives can be homemade by removing excess algae and aragonite and grinding them in a mortar and pestle.

Another example is a planted aquarium. A single display tank, a quality canister filter, a reverse flow under gravel filter, and fluorite ore substrate takes care of itself. Just replace evaporated water with water rich in potassium and phosphates, over feed the fish, and replace the lamps and filter floss twice a year. Plants take care of the rest.

Also, avoid adding extra heat to the aquarium. Use external pumps instead of powerheads. Acrylic aquariums can easily be machined to accept standard plumbing fittings. Make sure your plumbing has long radius turns and clean walls. Cooling your lights helps prolong lamp life and lowers water temperature. Place your heater inline with circulation plumbing. Make sure the entire tank is circulated. Dead spots make scary chemistry.

Many of the products available are marketed very, very well but provide little advantage if any to a less expensive alternative. So keep your wits about you and do your homework. In the end, your pets will be happier, your aquarium will look better, and you will spend less money.

Atlanta Aquascapes

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Comprehensive Lighting Guide

Why Lighting?

The simplest, most economic choice of lighting is sunlight. No tech aquarium folks believe there is no substitute. For many applications, aquarium lighting demands specific technology.

When you heat something, that something’s temperature goes up. At room temperature, this something will emit energy in the infrared (below red) range of light. However, hotter things emit light in the visible range (red to violet). Even hotter things may emit ultraviolet (above violet) light as well. The sun’s light is yellow. So, if you need something other than yellow light, then you need aquarium lighting.

What Lighting

Manufacturers standardize the spectrum of lamps using corrected olor temperature ratings (K) and color rendering indexes (CRIs). The K part tells you what color it looks like and the CRI part tells you how much it looks like that color.


Fluorescent lamps create large voltages across metal gases (fluors) in a coated tube. The electricity ionizes the gases and excites electrons in the gas. When these electrons relax, a little packet of light comes out called a photon. The coating on the tube is a material that absorbs UV light, and emits visible light. This coating largely determines the color of your lamp.

The phosphors degrade with use, and blue light intensity drops more quickly than red. So, lamps get darker and redder as time goes on. To maintain the blue and purple of a reef aquarium, lamps need to be changed at least twice a year; whereas the same aquarium may have red night lights that last a whole year.

There are only a few types of phosphors available. Many manufacturers use several coatings of different phosphors to achieve a balanced look. To achieve the most natural look, try to put as many different types of lamps in the canopy as possible. Most special bulbs accomplish the same thing as buying two daylight lamps and one cool white lamp (for example). The advantage to these special bulbs is that many people only have room for one lamp. There are exceptions to this rule and the number is growing, as some companies design aquarium lighting from the ground up instead of adapting existing technology to their needs.

The diameter of a lamp is very important. As the diameter increases, fabricating an effective reflector becomes increasingly difficult. The closer to a line source, where the diameter of the lamp is zero, the more effective a reflector will behave.

Balasts are designed for specific lamp types, and choosing a lamp also means limiting your choice of ballasts. The ballast determines the current and voltage to the lamp. A quality ballast will quickly pay for itself in reduced power bills and prolonged lamp life. Some ballasts have the option to attach a manual dimmer to the ballast. In conjunction with a timer, these ballasts can ramp light on and off to avoid the sudden firing of the lamp. Also, choosing a water proof ballast may come in handy.

Metal Halide

Metal halide lamps are essentially little fluorescent lamps on steroids. The metal halide gases are stored inside a coated quartz tube. This quartz is inside a glass shield to absorb UV light and provide a barrier if the quartz tube explodes. Instead of current flowing through the gas, the current actually arcs. This means higher temperatures and voltages. As such, metal halide lamps take a minute to start and then a few minutes to warm up. Basically, the ballast must start the arc and then vaporize everything inside the quartz sleeve. Probe start lamps have a small electrode inside the quartz tube to assist the firing the lamp. Pulse start lamps rely on the ballast to pulse the quartz tube to fire the lamp. Metal halide ballasts cannot be dimmed, unlike other types of lighting.

The color of the lamp is determined by the makeup of the halides and the phosphors coating the quartz tube. Pulse start lamps have a higher CRI, because the ballast is more gentle on the gases inside the quartz tube. Color ranges are nearly identical to fluorescent tubes; however, there are more options along the way. Metal halide lamps should last six months to a year. The blues in a metal halide lamp degrade very quickly. The most efficient metal halide lamps are near daylight. Because of this, many reefs rely on metal halide lamps for the daylight colors and fluorescent lamps for the purple and blue.


Light emitting diodes have come leaps and bounds recently. By 2008, new technology is scheduled to outperform all others (lumens per watt, lumens per dollar). There are still a handful of issues with LEDs, namely startup cost and color options. LEDs emit light in a very narrow range of colors, and the exact range of that color really depends on the batch and bin of the manufacturer. Also, initial costs of LED’s are quite high. Although, an individual LED is expected to have a lifetime of about ten years.

A handful of manufacturers sell LED lighting for the aquarium, but the nature of the wiring demands that an entire array of LEDs be replaced if a single burns out. And if you don’t replace the single array, then the others are not far behind. Thus, the benefits of LEDs are completely avoided. Basically, to save about 30% of the manufacturer’s costs, they ask you to replace $100 of LEDs when you really only need $5 replaced. A difficult fact to swallow when you’re already paying five to ten times as much as another technology, for the same amount of lighting.

One advantage of using LED lighting is the ability to program lighting intensity. The moon cycle, the seasons, cloud cover, sunrise, sunset, and anything else can be programmed into the lighting routine. This possibilities are huge with LEDs.


Lights are not 100% efficient. Therefore, lights create heat. This heat must be removed. If no efforts at ventilation are made, the the heat escapes via radiation. This may be adequate if the lamps are efficient and were designed to operate at elevated temperatures. Otherwise, ventilation may be required.

Simply drilling an array of holes above the lamps allows heat to escape through convection. This is adequate for most applications. However, often active ventilation is required. This involves placing a fan at either an input, an output, or both. If you are designing your own system, the ventilation that cools the lights can also be used to cool the aquarium water.

The Best Options

If you decide on the number of lumens you need, and then work backwards to how many lamps you need, then metal halide comes out on top. A metal halide lamp run by a pulse start electronic ballast puts out more lumens per watt and more lumens per dollar. However, in the next three months, the lamp’s luminosity decreases by 35%. In the same time, a T5 lamp’s luminosity will only decrease by about 6%. Also, consider that a quality reflector will direct about 80% of a metal halide lamps luminosity to the aquarium. A quality reflector for a T5 will direct over 90% of the light back. Notice, that the reflectivity of a reflector does not determine the amount of light reflected, but rather the probability an incident photon will be reflected. When you run the numbers again, T5 lighting comes out on top, by about 15%. Measurements with a light meter agree.

For a reef aquarium, most people want at least one metal halide. The real reason: metal halides look really cool. Reef aquariums usually have strong currents and surface waves. Metal halide lamps will make your reef sparkle, just like a real reef. Also, a single metal halide can provide a decent spectrum, whereas you really need at least two different color fluorescent lamps.

Compact fluorescent lamps provide a great alternative to T5 and metal halide lighting for smaller tanks. Reflectors must reflect light from more than one tube, which means that compact fluorescent lamps won’t perform as well as the corresponding straight tube lamps. However, bulb costs are lower, as a compact fluorescent lamp is essentially a longer lamp that is bent around.

By 2008, Atlanta Aquascapes plans on releasing a new LED lighting system for aquariums. This system will outperform all other lighting in terms of light output, light quality, and long term costs.

If you are looking for an economic option, then your local hardware store is the best place to start. Flat white paint has a reflectivity of about 95%, which is quite high. If you still have your high school geometry book, then you should be able to make your own reflector as well. Just find something relatively sturdy that you can cut with a razor. Watch out for silver materials when making a reflector. Some are excellent reflectors, and others are terrible.

Atlanta Aquascapes

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Acrylic vs. Glass

Acrylic vs. Glass

Acrylic has greater impact resistance than glass. Joining acrylic results in very strong bonds, and acrylic aquariums have been in service for decades without failure.

Acrylic can be machined very easily with the proper tools. Because of this, plumbing can enter from the bottom, back, or sides of an aquarium instead of only from above. Pumps work with a minimum of resistance, pulling water from anywhere in the aquarium and pushing anywhere else in the aquarium. This simple fact makes plumbing an acrylic aquarium clean and simple.

Acrylic insulates very well. If you run a heater or a chiller, then the water temperature in an acrylic aquarium will stay relatively constant with a minimum of power consumption.

Acrylic transmits over 90% of incident light. Also, acrylic has no color cast. Glass only transmits about 70% of light, and has a green cast. Because of these differences, acrylic aquariums always look brighter than glass aquariums.

Acrylic scratches easier than glass. Sharp rocks are best kept away from panes in the aquarium. Repairing scratches is possible, but requires the right materials and a little skill. Acrylic cannot be cleaned with glass cleaners. Always use a mild detergent and a clean cloth to clean acrylic.

Acrylic bends easily compared to glass. To ensure that acrylic panels stay true, the tops of acrylic aquariums are not fully open. Instead, a single piece of acrylic braces the sides with portholes in the center for access to the interior of theaquarium. A top brace can be avoided by using thicker plastic, but this costs significantly more.

Atlanta Aquascapes

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The Canister Filter

Basically, a canister filter allows a pump to suck or push water through filter media. The advantage largely is due to the ability to increase pressure within the filter. This means that each ounce of water can see a greater surface area while still maintaining adequate volumteric flow rates. Quality canister filters require little maintenance.

For a reef aquarium, canister filters are often overlooked. However, placing aragonite inside a canister filter inline with a reef aquarium increases the amount of calcium carbonate available to the reef. The canister filter provides an excellent method of buffering with little maintenance. Also, special mud can be placed inside the filter to provide trace elements and biodiversity to a reef. However, a canister filter alone won’t do the job in a reef aquarium. Volumetric flow rates (GPH) are very low from a canister filter, and other circulation and filtration systems should also be in place before adding a canister filter to a reef aquarium.

For a marine aquarium, certain fish will do just fine with a canister filter and nothing else. The result will be a still, calm aquarium with high water quality. Just make sure to buy fish that don’t like current and few enough not to overload the filter.

For the planted aquarium, the canister filter is often the filter of choice. Canister filters do not disturb the surface of the water, and do not mix water with fresh air. Because of this, valuable carbon dioxide and oxygen stay in the water instead of equilibrating with the air. Also, canister filters don’t provide strong currents, which is ideal for most plants. Connecting a canister filter to an overflow ensure that the water stays crystal clear.

Atlanta Aquascapes

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Protein Skimmers


Protein skimmers come in two basic flavors: counter current and cocurrent. Everything else is somewhere in between. A good skimmer will be as tall as possible, and have the air and water traveling in opposite directions. The volumetric flow rate through a skimmer is determined largely by the size and occupants of the display tank. The diameter of the skimmer is determined by the flow rate. Adding a venturi or a needle wheel may make a skimmer behave closer to a counter current skimmer, but the counter current skimmer always wins. The dirtiest air cleans the dirtiest water and the cleanest air cleans the cleanest water in a counter current skimmer.

If space becomes an issue, then other methods do win out over the counter current skimmer. Namely, downforce skimmers are excellent skimmers in a small package. Also, counter current skimmers require a little foresight when it comes to plumbing your aquarium. Make sure that if plumbing gets clogged or the power goes off that water doesn’t find the floor. Again, the downforce skimmer can be plumbed without these fears with ease.

Downforce skimmers also reportedly remove inorganic compounds from water as well as organic compounds. The violence of mixing air and water may be responsible, which is why other manufacturers try to mimic this effect with needle wheels and venturi. However, neither really approaches the same violence as a downforce skimmer. The major draw back to the downforce skimmer is that it is patented, on fairly simple terms. So, other manufacturers must pay royalties to the original designers. Because of this, downforce skimmers are often very expensive. Also, downforce skimmers should be placed in a sump area with a constant volume to achieve reliable results. This is unfortunate, because integrating a sump, trickle filter, and a downforce skimmer for very specific needs would be very simple; however, it would also be illegal.

Why Skim?

In a fish only tank, skimmers remove organic chemicals and floating debris from the water an an incredible rate. This means that the aquarium can be slightly over stocked without worry.

In a reef aquarium, skimmers make less sense. Often, an owner will feed corals with expensive foods that end up in the skimmer’s collection cup within thirty minutes. Skimmers take life and nutrients out of the tank, the exact opposite of the goal of a reef aquarium. In the oceans, phytoplankton feed on upwelling currents rich in nutrients. These currents often swing by reefs, carrying the phytoplankton and nutrients with them. When the current leaves the reef, very little phytoplankton and nutrients remain. In a sense, the natural role of the reef is to filter the ocean. So, why do people skim reefs, when reefs naturally filter themselves?

The answer is usually overstocking with fish. More fish means more fish food. More fish food means more fish waste. The skimmer removes fish waste with ease. However, a refugium removes fish waste and fish food more quickly than a skimmer, and there is no way to over filter using a refugium. The cost of a refugium is low because aesthetics aren’t important, only function. The refugium essentially turns waste from the display tank into food for the display tank. It can be a great place to cure live rock, introduce new pets to water chemistry, separate injured pets, frag corals, and a million other functions.

The skimmers still has a place in the reef aquarium. A skimmer provides an excellent backup to the refugium. For example, if you rely on macroalgae, then you may need to thin the crop periodically. When you do this, the refugium doesn’t operate at the same level because a chunk of the photosynthetic macroalgae just disappeared. While the refugium adjusts, water quality may drop. If it does, then having a skimmer on hand can avert a disaster. In such cases, I recommend buying a skimmer that turns over the water in the aquarium every hour. This way, the skimmer can be run once a day for brief periods of time to control water quality.

In the freshwater world, skimmers have less use. This is largely due to the fact that skimmers rely on the salts in the water to form a foam. In freshwater, making the foam is difficult, and results suffer. Never the less, many freshwater tanks run skimmers with great success.


Using air enriched with ozone in a skimmer provides a very interesting filter. Ozone increases the reduction-oxidation potential of the water. Think of ozone as the Vitamin C of the aquarium. My favorite setup with ozone turns the water over once a day. This way, ozone concentration is minimal, but oxygen concentrations are still high. Remember, ozone isn’t really present in oceans. Putting ozone in the skimmer means putting oxygen in the aquarium. So, ozone can increase the oxygen levels too much, or worse yet increase ozone concentrations too much. If used properly, skimming with ozone can produce amazing results.

The first step to making ozone is a source of dry air. There are many desiccants available, and some even change color as they absorb water. Once the air is dry, you can make ozone from oxygen in the air. To do so, you can simply arc electricity across the air. A more safer, sophisticated approach is to irradiate the air with UV light. Since air flow rate is important to the skimmer, adjusting the flow of air may not be an option, Instead, you can adjust the amount of ozone in the air by shielding the air from the UV light. Then, you simply need to plumb the ozone to a skimmer than can handle ozone. Test for ozone concentration using pool test kits, or alternatively you could measure the reduction-oxidation potential with a solid state device. Either works fine, and both have pretty major drawbacks. The point here is to slowly increase ozone levels to ensure the safety of your pets.

Atlanta Aquascapes

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Book Review: Aquatic Systems Engineering: Devices and How They Function

This is a review of the new CAS library book, Aquatic Systems Engineering: Devices and How They Function, by P.R.Escobal. The author is an aeronautics engineer that left the field to form the companies Aquatronics and Filtronics, manufacturers of “high-end” aquarium filtration, aeration, and sterilization equipment.

The book discusses the use of these items in setting up an aquatic environment: both single tank and multi-tank systems. The proper sizing of components is discussed in detail, and mathematical rigor is used. This book is therefore not light reading: in fact, tables, schematic diagrams, and calculation make up the bulk of the book.

The calculations are however complicated by the exclusive use of American Imperial units throughout the book, rather than the much simpler SI units. As the author is American, this is understandable, but even American engineers will nowadays calculate in SI and (if required) convert the result to antique units after it is found.

After an introductory chapter that defines the terms used throughout the book, the meat of the book begins with a surprisingly complicated discussion on how to determine the time required for passing all of an aquarium’s water through a device (such as a filter). The complication arises from the fact that the water from the filter is mixed with unfiltered water on return to the aquarium. It is shown that all of the water can never be filtered in such a set up, but 99.99% of it is effectively filtered after the volume of water is cycled through 9.2 times. One can safely round this to 10 times, and say, for example, that a 100-liter per hour filter would require 10 hours to filter all the water in a 100-liter tank. The commonly used aquarist “rule of thumb” is to use a filter that pumps the aquarium’s water volume two to three times per hour, reducing the filter time to about four hours.

The next chapters deal with the proper sizing and operation of ultraviolet sterilizers. It is here that the author shows his biases. Chapter three opens with the sentence “Fishwise, the single most important device available today, ranking second only to a well designed mechanical filter system is the ultraviolet sterilizer”. Even setting aside this statement’s self-contradiction, I find this declaration odd to say the least: the vast majority of successful amateur aquarists don’t even use an UV sterilizer so they clearly can’t be that important. And the mention of a mechanical filter I also find odd, because I only use them as a prefilter to my biological filter, which I would surely rank as the most important aquarium device anyone can have.

If the opening statement was meant to boost sterilizer sales then I am afraid that in my case, at least, it has failed, since the contents of the sterilizer chapters have convinced me not to buy one. The discussions on “dwell time” and “zap dosage” clearly show the futility of using a small UV sterilizer in a moderate to large sized aquarium system. For example, a 25-watt UV sterilizer (itself costing about $250) can only be useful on a 180-liter or smaller aquarium, and then only if the flow rate through the sterilizer were carefully regulated. My 500-liter show tank would require 64 watts of UV to be effectively sterilized at a cost of nearly $1000 (including pump, flow monitor, and plumbing). Since I have never seen any of the diseases that UV sterilization is supposed to prevent, this expense hardly seems justifiable. However, to anyone deciding on using an UV sterilizer, I would say that these chapters are required reading, as they convincingly demonstrate that careful matching of the tank capacity, sterilizer wattage, and pump flow rate is required for satisfactory results. You simply can’t stick any old sterilizer to the output hose of your canister filter and expect effective sterilization.

The following chapters discuss the design and operation of protein skimmers, and should required reading for anyone wanting to design such a device.

There is also a chapter that discusses heating and cooling of aquaria. Heat loss from a model aquarium is examined and examples are given as to how to determine the heater wattage needed for a given tank. This information is potentially very useful, but unfortunately it doesn’t adequately address all the complications that arise from extraneous heat coming in from the lights or water pumps, or the complex configurations of multi-tank systems, or of open-air tanks that suffer from evaporative heat loss. So in the real world, you would still probably have to rely on trial and error when sizing a heater for a multi-tank system.

Two points do however become quite clear while reading the chapter on aquarium heating: acrylic tanks require much smaller heaters than do glass tanks, and
“watts per gallon” heater sizing rules are useless. Heat is lost from the tank proportionally to its surface area, not its volume. So even though beginner books may advocate buying a heater big enough to supply “5 watts of heat per gallon”, and even though this may be fine for a 10 gallon tank (50 watts of heat), it results in serious overkill in 100 gallon tank, where 500 watts of heat will cook your fish.

The chapter discussing water pumps is also informative, but is hampered because it discusses pump performance in terms of output pressure. Unfortunately pump output pressures are almost never given for hobbyist pumps. Instead, pumps are rated by flow rate…either at a variety of “heads” (if you are lucky) or as a single value. The pump “head” is the height the water is lifted by the pump, but many aquarium pumps are designed strictly for “flat flow”, or zero head. Such “circulation pumps” are only given a passing mention.

For those pumps that are rated for pump flow at various heads, it is easy to determine the pump pressure, but the relevant equation is not provided in the book. So here it is…let

P = pump output pressure in Pascals.

z = be the height in meters where flow rate drops to 0 (the maximum head).

d = density of water (which is 1000kg/m3 for fresh water)

g = gravitational acceleration (which is 9.8 m/s2 near the Earth’s surface)

then P = d g z

= (9800 kg m^2 s^2) z

To convert pressure in Pascals to PSI, multiply the pressure in Pascals by 0.000145 PSI/Pa. You can also make a quick estimation of the pressure by remembering that every meter of head requires the addition of about 1/10 of an atmosphere of pressure, where 1 atmosphere is about 1000 Pascals or 14 PSI. For example, my pond pump is reported to pump to a height of 8 meters, so it must deliver about 11 PSI.

Once the pressure of the pump is determined along with the diameter of the pump outlet, the flow rate at any head is easily determined from the formulae presented in this book. But much more importantly, the book also presents the information required to allow you to design a real filter system, taking into account the losses of flow due to friction in your hoses and connectors.

This information is to my mind the most universally applicable information in the book, as the most complicated piece of “aquatic engineering”” that the advanced hobbyist is likely to attempt is a single-pump, multi-tank fish room. Everything you need to know about sizing and designing such a room is included in this book, and I don’t think anyone should attempt it without first having a thorough read.

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pH Probe Cleaning and Calibration

Although I think a pH meter is pretty much essential for a reef tank, its not much use unless the meter is correctly calibrated.
General Comments

Never wipe the probe tip, to remove water droplets, blot the tip with kitchen paper or shake the liquid off.
A new pH probe

Before using a pH probe for the first time, check that the sleeve that the probe tip came in is full of liquid. If it is dried out then return it to your supplier. To condition the probe before use, soak the probe in either pH 4 or pH 7 buffer for 20 minutes, then rinse with RO or DI water. Then you are ready to calibrate.
pH probe cleaning

The safest way is to soak the probe in white vinegar for an hour or more. The easiest way is to soak the probe in 0.1M HCl for 20 minutes. Every so often it is worth removing the bacterial film build up. To do this, mix 1 part household bleach with 10 parts water and soak for 10 minutes. Rinse with RO or DI water and you are ready to calibrate.
pH probe calibration

Having cleaned your pH probe, you need a good thermometer, fresh calibration fluids and a small jug of RO or DI water. I much prefer pH sachets to bottles as they are always fresh. As soon as you open a bottle of pH calibration buffer, it starts to age. Stick with sachets. I use those from Hanna as they have both a use by date and a chart that shows pH vs. Temperature.

Next, throw the unopened pH calibration sachets in the sump to come up to tank temperature, this only takes a few minutes. At the same time get a mug and fill it full of tank water. After five minutes empty the mug and refill with more tank water, the mug of water helps minimise temperature change. Carefully open the pH sachets and place them in the mug of tank water. Put your accurate thermometer in the water in the mug.

Put the probe into the pH 7 solution, stir gently for a few seconds and then go make a cup of coffee or something that keeps you occupied for 10 minutes. Come back and adjust the meter to the correct pH. Rinse the probe in RO or DI water, blot or shake dry, then place the probe in the pH 4 or pH 10 solution, again stir gently for a moment and have another coffee. After 10 minutes adjust the pH meter (check your thermometer in case of temperature changes!). Rinse the probe, dry and stick it back in the pH 7 solution, having stirred and left for 2 or 3 minutes it should read correctly within 0.01 or so. If so then rinse and put in service, otherwise repeat the calibration.

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Operating a Calcium Carbonate Reactor

Having had a reactor for a number of years now and gone through all the trials and tribulations, I thought it might be helpful if I record my experiences.

There are three main things that have been a problem.
1. Getting a constant drip rate
2. Getting a constant CO2 bubble rate
3. Dealing with a suppressed pH level in the main tank

1. Constant Drip Rate

Although the various designs of reactor may be better or worse for this, it is generally true that it very difficult to achieve a constant drip rate using a normal pump. Eventually they slow down and you end up constantly have to adjust them. There are two potential solutions.

The first one, which I have not used, is to take a line off the main return pump and control the flow using a micro gate valve. The high pressure produced by the main pump makes it less susceptible to changes and the gate valve allows precise control.

The second way, which I use, is via a dosing pump, in my case a peristaltic pump. Dosing pumps are nice because they are small, do not require any clever plumbing, produce a high pressure and do not need to be primed. In the case of peristaltic pumps, all you have to do is replace the special tube regularly (monthly in the case of silicon tube).

2. Constant Bubble Rate

The next problem I had was getting a reliable bubble rate. This was because I tried to save some money and bought a regulator from the local welding supply place. Sadly although it is probably fine for the rates required for welding, it was hopeless at the very slow bubble rates needed for a reactor. I bought a proper two stage unit with a needle valve and never looked back. For your information, I bought a Bioplast unit.

3. Low pH

Because CO2 is used to lower the pH in order to dissolve the reactor media, the chances are excess CO2 comes out of the reactor. With sufficient water surface agitation and fresh air coming into the room, then you may be able to get away with it. However this proved impossible for me.

Therefore, what I have found works really well is to add a second chamber to the reactor. Unlike the main chamber, water is not recirculated, all that is needed is the outlet of the main chamber to be connected the bottom of a second tube full of reactor media.

This second chamber does not need to be anything fancy. I used an old DI column, but if you have an old canister filter that feeds in at the bottom then the greater volume would make that an ideal choice (do not turn its pump on though!). The only suggestion I would make is to use one of the more easily dissolved media in the second chamber. I use CaribSea Geo-Marine for all my media which is fairly soluble, unlike the “proper” (more pure) media like Koralith. CaribSea also do a special media called ARM which is even more soluble but its price is so much more than the standard Geo-Marine that I have not bothered.

Because you are using the CO2 more efficiently then you may need to retune your reactor (less CO2 is needed). This method also works quite well if you reactor is undersized for your tanks requirements.

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