How to Choose Aquarium Equipment

Technical know-how increases your chance of a successful aquarium. See more aquarium fish pictures.
Technical know-how increases your chance of a successful aquarium. See more aquarium fish pictures.
©2007 Publications International, Ltd.

Fishkeeping is really more of an art than a science. As a true aquarist, you'll develop an appreciation for the beauty of the hobby and a certain respect for the creatures in your tank.

You'll come to view your aquarium not as a pastime or as an attractive addition to your living room, but as a delicate, vibrant system that takes shape and comes to life through your efforts, skill, and vision.


Aquarium Fish Image Gallery

Like all arts, though, fishkeeping does have its technical side. To succeed, you have to create a suitable habitat for your fish, and to do that, you must use the proper tools. Knowing how your aquarium equipment works and why you need it will greatly increase your chances of success.

When planning your aquarium, keep in mind that you probably won't need all of the items that appear in the following pages. Consult with your dealer to determine which pieces of equipment are necessary to create the kind of aquarium you want.

Let's start by learning about aquarium filtration on the next page.To learn more about freshwater aquariums, see:

Aquarium Filtration Overview

The more effective the filter material is at trapping small particles, the more often you will have to clean the filter.
The more effective the filter material is at trapping small particles, the more often you will have to clean the filter.
©2007 Publications International, Ltd.

As soon as fish are added to an aquarium, the normal processes of respiration and digestion produce waste products that pollute the water. There are also other sources of pollution, such as decaying uneaten food.

The biggest challenge in keeping an aquarium is controlling the level of these pollutants so that your fish have a healthy environment. One of the things you need to meet that challenge is an effective aquarium filtration system.


In many ways, aquarium filtration is the most complicated and difficult aspect of fishkeeping. A visit to any well-stocked aquarium or pet store will reveal an astonishing array of filters that vary widely in design and price.

In addition, the beginning aquarist faces a lot of new terms that are used to describe filters. Understanding how filters work and what they accomplish can make it much easier to sort through everything.

You may assume that the basic goal of filtration is to remove debris floating in the water so that it doesn't cause pollution. While this is correct, it's only part of the story.

This process is mechanical filtration. If mechanical filtration is sufficient, very little solid matter will be left floating in the water. However, just because the water looks clean doesn't mean it is safe for fish.

Most of the pollution that causes the water quality to deteriorate can't be seen. In order to remove it, two other types of filtration are needed: chemical filtration and biological filtration.

Only when mechanical, chemical, and biological filtration are available can a truly healthy environment be maintained for the fish. Aquarists often use two different filters together in order to provide these three types of filtration. This is because filter designs that are very good at providing one or possibly two types of filtration tend to be less effective at providing the remaining types.

Go to the next section to learn more about mechanical filtration.

To learn more about freshwater aquariums, see:

Mechanical Aquarium Filtration

You must control water pollution in an aquarium to ensure your fish remain healthy.
You must control water pollution in an aquarium to ensure your fish remain healthy.
© Leino Ole

Mechanical aquarium filtration is accomplished by moving water through some kind of material that acts like a sieve, catching the solids and removing them from the water. Ideally, the most effective mechanical filter removes particles down to very small sizes, but there is a trade-off here.

The smaller the particles are that the filter removes, the faster the filter material will clog. Because clogged filter material severely reduces the rate of water flow through it, the material must be cleaned or changed. The more effective the filter material is at trapping small particles, the more often you will have to clean the filter.


For this reason, most filter material is designed to catch only the larger, more visible solids. Of course, as the filter material catches large particles, the openings in the material through which the water flows become increasingly smaller and thus trap increasingly smaller particles. The material does clog eventually, but it takes much longer.

Let's explore another type of aquarium filtration -- chemical filtration -- in the next section.

To learn more about freshwater aquariums, see:

Chemical Aquarium Filtration

You may need chemicals to help filtrate your aquarium water.
You may need chemicals to help filtrate your aquarium water.
©2007 Publications International, Ltd.

Chemical aquarium filtration is needed because a number of dissolved, invisible compounds accumulate in aquarium water and they can't be removed by mechanical filtration.

These compounds are not toxic to the fish but can inhibit their growth and cause chronic, low-level stress that eventually leads to disease. Most of these compounds are dissolved organic substances produced by natural biological decay.


The dissolved organic substances eventually reach concentrations high enough to become visible as a yellowish tinge in the water. You can see this when a sheet of white paper is held behind the tank so that half of it is viewed through the water.

If the water is healthy for the fish, the paper viewed through the water will be as white as the other half; if not, the paper will have a yellowish cast to it.

Chemical filtration removes many, but not all, of these compounds. However, some substances that affect the growth of the fish can only be removed by making partial water changes on a regular basis.

If this isn't done, the fish will never grow to normal adult size. This stunted growth will result in fish that never achieve the beauty of mature fish, and it can cause other related health problems.

There are many ways to accomplish chemical filtration, but for all practical purposes, the only method that is both effective and relatively economical is to pass the aquarium water over granular activated carbon.

Granular activated carbon is usually made from an organic material, such as coconut shells, that is ground into small pieces and then heated to 2,000° Fahrenheit to drive off gases in the material. This "activation" produces carbon that can adsorb the molecules of compounds in the water and hold on to them. Adsorption is the adhesion of a thin layer of molecules to a solid (in this case, the activated carbon).

The carbon eventually becomes saturated with molecules and must be replaced. It cannot be reactivated by hobbyists because of the special ovens needed for the process.

Granular activated carbon should not be confused with charcoal, which is sold in some stores at a much lower price but does not provide effective chemical filtration.

There are a few things to keep in mind when using granular activated carbon. The smaller the granules of carbon, the greater the total surface area available to adsorb molecules for any given amount of carbon. The total surface area of the carbon determines how long you can wait before it is necessary to replace it.

A good rule of thumb is to use one ounce of carbon for every four gallons of water. If the tank is not overstocked with fish, the carbon should last at least a month and probably twice that.

See the next section to learn about biological aquarium filtration.

To learn more about freshwater aquariums, see:

Biological Aquarium Filtration

In many ways, filtration is the most complicated aspect of fishkeeping.
In many ways, filtration is the most complicated aspect of fishkeeping.
©2007 Publications International, Ltd.

The third type of filtration -- biological aquarium filtration -- is the most important of all. The lack of effective biological filtration is probably responsible for the deaths of more fish than any other cause. The particular dissolved compounds controlled by biological filtration are very toxic to fish even at low concentrations.

In newly set up tanks, the effects of these compounds can kill fish very quickly. In aquariums that have been running longer but are overstocked with fish, there can be constant low levels of these compounds in the water. This creates chronic, long-term physical stress, resulting in diseased and dying fish.


To understand biological filtration, it is necessary to understand a basic process in the aquarium: the nitrogen cycle. Ammonia is one of the key elements in the nitrogen cycle. Fish produce ammonia directly both as a by-product of respiration and as a waste product from the digestion of foods.

Solid wastes are also converted into ammonia, which is why it is important to remove them with mechanical filtration. Uneaten food, plant materials, and other organic items that decay in the tank are also converted to ammonia.

Ammonia, a nitrogen-based compound, is extremely toxic. In an aquarium, it can build up quickly and threaten all the fish in the tank.

Nature, as usual, has a solution to the problem. A species of bacteria known as Nitrosomonas will actually consume ammonia, as long as there is enough dissolved oxygen in the water to support the bacteria.

Nitrosomonas bacteria are everywhere, so you don't even need to add them to the aquarium; they will grow there naturally. However, it takes them a while to multiply to a population size capable of consuming all the ammonia in the water.

As the Nitrosomonas consume the ammonia, they convert it to nitrite. Nitrite is also toxic to fish and in the long run tends to be a larger problem than ammonia.

Another species of bacteria, Nitrobacter, will consume the nitrite and convert it to nitrate, a relatively harmless compound that can be used up by plants and algae.

As with Nitrosomonas bacteria, it takes some time before the Nitrobacter are able to multiply to sufficient numbers to handle all of the nitrite. Unfortunately, until the Nitrosomonas are able to increase to numbers sufficient to control the ammonia in a new aquarium, the high ammonia levels inhibit the growth of Nitrobacter, thus allowing the nitrite levels to increase quickly and remain high.

While it may take a week or less for the population of ammonia-consuming Nitrosomonas to grow to sufficient numbers, the delay in Nitrobacter growth means it can be six weeks or more before nitrite is under control.

This process of starting the nitrogen cycle, which generally takes a total of six to eight weeks, is known as "breaking in the tank." If there are too many fish in the tank during this process, and not enough water changes are made, many of the fish will die.

This situation is known as "new tank syndrome." It's also the reason so many new hobbyists are unable to keep their fish alive and healthy.

Some aquarists report that they successfully break in their tanks using fish, but add a one-step water conditioner that neutralizes the toxic ammonia. The neutralized ammonia can still be consumed by the Nitrosomonas bacteria so they can multiply, but it will pose no danger to the fish.

However, the Nitrosomonas bacteria will still produce nitrite, and the fish will have to battle the increasing concentrations of that chemical until the Nitrobacter colony is established.

The end product of the nitrogen cycle -- nitrate -- will not harm fish unless it reaches rather high levels. Because nitrate can be used by plants as food, live plants will help control nitrate levels. Without aquatic plants, however, the nitrate will be used as food by simpler plants -- algae.

One way of controlling problems with excess algae is to lower the nitrate level by making partial water changes, which should be a normal part of aquarium maintenance anyway.

Check out the next section to learn about aeration and surface agitation.

To learn more about freshwater aquariums, see:

Aquarium Aeration and Surface Agitation

At the surface level of an aquarium, water and air undergo a natural exchange of gases.
At the surface level of an aquarium, water and air undergo a natural exchange of gases.
©2007 Publications International, Ltd.

Before looking at specific filter designs, you should understand aquarium aeration and surface agitation.

At the surface level, water and air undergo a natural exchange of gases. Oxygen goes from the air to the water, and carbon dioxide goes from the water to the air. This is how the oxygen that fish breathe enters their habitat and how the carbon dioxide that they produce by respiration is removed from their habitat.


When the surface of aquarium water is disturbed, the rate of gas exchange between the water and the air is increased; more carbon dioxide is released into the atmosphere and more dissolved oxygen is taken by the water. The surface tension of the water must be broken for sufficient gas exchange.

Fortunately, creating surface agitation is easily done with aeration, or pumping air into the water so that it forms bubbles. The bubbles rise to the surface and burst, thus breaking the surface tension.

This also creates water movement in the tank, in effect stirring the aquarium ever so slightly, so that all of the materials and compounds in the water -- both the beneficial ones and the harmful ones -- are evenly distributed throughout the tank.

One way of providing the necessary aeration in an aquarium is to use air stones connected to an air pump. The air stones can be made from wood or other highly porous materials. When air is forced in one end of the air stone by the pump, it is released as bubbles from the other end.

Many filters, however, use air bubbles as a part of their design. As air bubbles move upward, their movement causes water to rise up with them, in effect creating a current that circulates all the water in the tank. These air-lift filters use this technique to pull water through their filter media and thus clean the entire tank.

Any filter that uses air bubbles to operate will provide the aeration, as long as the bubbles are driven with enough air to actually break the surface tension of the water. Filters that do not use air bubbles to create circulation often have available attachments that provide aeration.

Go to the next page to learn about the different types of filter designs available.

To learn more about freshwater aquariums, see:

Aquarium Filter Designs: Box, Power, and Canister Filters

There are lots of tools required to build a healthy freshwater aquarium.
There are lots of tools required to build a healthy freshwater aquarium.
©2007 Publications International, Ltd.

Mechanical aquarium filters all serve the same function, but they come in a variety of different designs: inside box filter, inside power filter, outside power filter, and canister filter.

Each type of filter has its own system for creating water flow, and each type has its own advantages and disadvantages. All will work well depending on the capacity of the filter, the size of the tank, and the amount of maintenance the filter receives.


Nearly all mechanical filters also have a compartment to hold activated granular carbon, so that they act as efficient chemical filters as well.

To avoid having the carbon become covered with solid matter, which would keep it from adsorbing the chemical wastes, the water should pass through the mechanical filtering material first. That way, the solid matter will be removed from the water before it reaches the carbon.

The inside box filter is the simplest and least expensive of all mechanical filters. The filter is set up inside the aquarium itself, and it can be relatively effective in smaller tanks.

Bubbles from a tube or air stone inside the box draw water through it. The bubbles rising to the surface from the box also help aerate the tank. The box itself is filled with Dacron filter material and a quantity of granular activated carbon.

There are a few drawbacks to the inside box filter. It is not very effective in large aquariums. From a visual standpoint, it adds nothing to the appearance of the tank, although it can sometimes be hidden successfully behind plants or a large rock. Also, changing the filter material requires removing the unit from the tank.

The inside power filter is similar to the box filter except that a motor pumps water through the filter at a much faster rate. The greater flow rate will act to improve filtration.

As with the air-driven box filter, though, visual appearance and maintenance are drawbacks. In addition, you will probably also need air stones to provide sufficient aeration for the tank.

Proper aquarium filtration may take some time to master.
Proper aquarium filtration may take some time to master.
©2007 Publications International, Ltd.

An outside power filter hangs on the back of the tank and has intake and outflow tubes that sit inside the tank. An outside power filter offers many advantages over internal filters.

Because it is behind the tank, the filter itself cannot be seen, although the intake and outflow tubes will be somewhat visible. The boxes of these filters are large, too, so more filter material and granular activated carbon can be used, increasing the amount of mechanical and chemical filtration.

Also maintenance of these filters is usually much easier because they are not submerged in the aquarium.

Some outside power filters use cartridges or bags of carbon that are prefilled by the manufacturer. If the cartridge or bag doesn't fit tightly in the space allocated for it in the filter box, the effectiveness of the chemical filtration will be reduced. This is because water takes the route of least resistance, and it will flow around the cartridge or bag if there is space rather than being forced through the carbon.

To remedy this situation, slit open the cartridge or bag and fill it with more carbon. This will create a tighter fit while providing more carbon for chemical filtration.

Outside power filters also have much higher flow rates. In order for mechanical and chemical filtration to be effective, the filter should process the volume of the tank four to five times each hour. In larger tanks, these flow rates are only possible with outside power filters and canister filters.

Canister filters differ from outside power filters in that hoses transport the water from the tank through the filter and then back to the aquarium. The canister filter can sit under the tank or on a shelf, although some have optional brackets to attach the filter to the back of the tank.

As a general rule, canister filters cannot move as much water as outside power filters, primarily because of the length and diameter of the hoses. In addition, some aquarists believe that canister filters are more difficult to maintain than outside power filters.

One unique type of canister filter is the diatomaceous earth filter. Some regular canister filters have special inserts for this purpose, whereas others are designed specifically for this kind of filtration.

Diatomaceous earth (a very fine white powder) is used to coat a special material in the filter through which the water flows. The filter is run for two or three hours, during which time the gravel is stirred occasionally to release any solid matter in it. Extremely small particles can be removed with this type of mechanical filtration, making the water very clear.

A diatomaceous earth filter is not designed for continuous operation because the filtration material clogs within hours.

Learn about another aquarium filter design -- undergravel filters -- in the next section.

To learn more about freshwater aquariums, see:

Aquarium Filter Designs: Undergravel Filters

An undergravel filter is relatively inexpensive, reliable, and very effective.
An undergravel filter is relatively inexpensive, reliable, and very effective.
©2007 Publications International, Ltd.

Biological aquarium filters, including undergravel filters, function in a completely different way, and they have a completely different design.

The Nitrosomonas and Nitrobacter bacteria necessary for biological filtration will colonize virtually every surface in a tank. However, there is usually not enough surface area in a tank to support populations of these nitrifying bacteria large enough to process all the ammonia that is produced in a typical aquarium.


A biological filter deals with this problem by making the natural nitrogen cycle operate more productively.

A biological filter has two main functions. It increases the amount of surface area available to the nitrifying bacteria, and it creates a constant flow of aquarium water over the colonized area.

The most popular kind of biological filter is the undergravel filter. It is relatively inexpensive, reliable, and very effective.

An undergravel filter is really just a plastic plate that covers the bottom of the aquarium. The plate has many small holes or slots in it. The exact physical appearance varies from one brand to another, but all work on exactly the same principle.

The undergravel filter plate is covered with aquarium gravel. Located at each back corner of the plate is a lift tube that extends from the plate to the top of the tank.

The aquarium water is drawn up the lift tube along with bubbles from an air stone at the bottom or by a small motor, called a powerhead, at the top. This pulls water from under the plate, which in turn draws water down through the gravel.

As the water passes across the grains of gravel, the nitrifying bacteria living there use the dissolved oxygen in the water to metabolize the ammonia and nitrite. The grains of gravel offer a huge total surface area for the bacteria to colonize, and the steady water movement ensures that enough oxygen will be available to support the large colonies.

As a result, the aquarium will house more than enough nitrifying bacteria to complete the nitrogen cycle, and the fish will have a healthy environment.

In addition to being a biological filter, the undergravel filter acts as a mechanical filter because it catches solids as they pass into the gravel bed.

Unfortunately, this actually works against the biological filtration process because as the spaces between the pieces of gravel fill with particles, the flow of oxygenated water past the bacteria is reduced. Over time, the effectiveness of the biological filtration is significantly impaired.

This problem can be solved by using a separate mechanical aquarium filter to remove many of the particles before they become buried in the gravel bed, and by cleaning the gravel when doing water changes.

An undergravel filter does not function as a chemical aquarium filter. Some undergravel filters are equipped with small cartridges of granular activated carbon that sit at the top of each lift tube, but these should be discarded for two reasons.

First, there isn't enough carbon in these cartridges to last more than a few days at the most. Second, these cartridges reduce the flow of water through the filter significantly.

Go to the next section to describe one last aquarium filter design, sponge filters.

To learn more about freshwater aquariums, see:

Aquarium Filter Designs: Sponge Filters

The balance of an aquarium's environment is delicate.
The balance of an aquarium's environment is delicate.
©2007 Publications International, Ltd.

Another kind of biological aquarium filter that is commonly used in aquariums is the sponge filter. Although varying somewhat in appearance, all sponge filters work the same way.

Water is pulled through the sponge, which is colonized by nitrifying bacteria. Most sponge filters use a single lift tube and air bubbles to draw water through the sponge, although some large models can use a powerhead instead.


There are specific reasons for using sponge filters. For example, if you keep a sponge filter in a tank that already has a biological filter, it will develop its own colony of bacteria. The sponge filter can then serve as an emergency biological filter in another tank.

If you need to set up a small tank to treat a sick fish or a quarantine tank for new fish, the sponge filter can provide immediate biological filtration for that tank. This eliminates the usual break-in period.

For those who breed fish, the sponge filter is also very useful. Often at some point, young fish need to be taken out of the adult tank and put into a fry tank, which contains only juveniles of the same size. Sponge filters provide instant biological filtration for the fry tank.

It is safe for the baby fish because there is no dangerous filter intake, as with power filters, and the micro-organisms on the surface of the sponge even provide an additional food source for the growing fish.

It should be mentioned here that all mechanical filters eventually function as biological filters. That is, the mechanical filter material and the granular activated carbon will become colonized by nitrifying bacteria.

However, by the time the mechanical and chemical filtration materials are fully functioning biological filters, they will need to be removed and replaced as a normal part of filter maintenance.

The only exception to this is when foam or sponge is used as the mechanical filtering material. Then, the material can be squeezed gently several times in a bucket of aquarium water and placed back in the filter. Most of the nitrifying bacteria will survive this procedure and reform the colony.

Because outside power filters and canister filters have more room inside, there is often space for special materials that can provide biological filtration. Ceramic noodles, rings, and other shapes offer lots of surface area for nitrifying bacteria to colonize. These items can be rinsed in aquarium water without removing or killing the bacteria.

Undergravel filters or sponge filters provide the most efficient biological filtration, but if such units are impractical or unavailable, using an outside power filter for biological filtration will work. For very large aquariums, two or more outside power filters or canister filters can be used.

See the next section to learn to ensure your aquarium water is at an optimum temperature.

To learn more about freshwater aquariums, see:

Aquarium Water Temperature

Water temperature should remain consistent in your aquarium.
Water temperature should remain consistent in your aquarium.
©2007 Publications International, Ltd.

For the vast majority of tropical fish, an aquarium water temperature of 76 to 78º Fahrenheit will be fine. Some species like cooler water and some prefer warmer water, but as a compromise, this range works well.

If you are having difficulty deciding what fish to buy, it wouldn't hurt to choose fish that prefer the same temperature range. Goldfish are not tropical fish and fare better at temperatures closer to 65º Fahrenheit.


It is very important that the water temperature be consistent. Rapid fluctuations in temperature, particularly down, cause physical stress to fish that often leads to disease. The solution to maintaining the correct water temperature is an aquarium heater and thermostat.

Aquarium heaters are available in a variety of types, sizes, and prices. When it comes to aquarium heaters, trying to save money is not a good idea. The reliability of a heater is too crucial to risk buying an inexpensive one.

The weak link in any heater is the thermostat, which regulates the heater, turning it on and off to maintain the desired temperature. The quality of design, materials, and construction of the thermostat is one of the things that separates unreliable heaters from good ones. In cheap heaters, the thermostat often sticks -- either open or closed -- and this can be disastrous.

When the thermostat is stuck in the closed position, the heater remains on, raising the water temperature. Unless you make a habit of checking the temperature each day, you may not notice there is a problem until the fish have died, either directly from the heat of the water or because the warm water is unable to hold enough dissolved oxygen to support them.

If the thermostat sticks in the open position, the heater never turns on and the water temperature begins to drop. How low the temperature will drop depends directly on the room temperature.

In the summer, when the room may be in the 70º to 80º Fahrenheit range, the temperature may not even drop at all.

Learn more about aquarium heaters on the next page.

To learn more about freshwater aquariums, see:

Aquarium Heaters

Choose fish that like the same water temperature to make your life easier and your fish happier.
Choose fish that like the same water temperature to make your life easier and your fish happier.
© Anne Norman

As a general rule, the more water a tank holds, the more stable the aquatic environment will be. For example, it will take a 50-gallon tank much longer to drop in temperature than a 10-gallon tank.

The same is not true for temperature increases, though, because the aquarium heater wattage is chosen to match the size of the tank it will be in. The rule of thumb is five watts per gallon, which will allow the heater to raise the temperature of one gallon of water by one degree Fahrenheit in one hour.


Thus, a 10-gallon tank would use a 50-watt heater and a 50-gallon tank would use a 250-watt heater. For larger tanks it is often necessary to use more than one heater to achieve the desired wattage.

In fact, using more than one heater is actually a good idea for any size aquarium in terms of safety. When two smaller heaters are used that equal the wattage of one heater, the possibility of complete heater failure is almost eliminated.

If one heater should stick in the closed position, the temperature will rise only half as fast, giving you a greater chance of catching the problem before it becomes serious. If one of the heaters sticks in the open position, the other heater will prevent the temperature from dropping as far or as rapidly.

A complete heating system must also include a thermometer so that you can monitor the temperature of the tank. Either the normal red-alcohol variety for inside the tank or one of the digital types that sticks on the outside of the glass will work.

Because there is a range of accuracy among these thermometers, look at several of them and pick one that seems to show a reading in the middle of the range or that shows the most common reading.

There are two basic aquarium heater designs. One hangs into the water from the frame of the tank and the other is completely submersible and can be placed anywhere in the aquarium, usually by using suction cups to stick it on the tank. With either design, there is always a waterline mark on the body of heater that indicates how much of the heater must be in the water for it to operate properly.

The mark is very important. Should the heater be plugged in without the water up to the mark, the heater could stay on and become very hot, possibly causing damage.

Lighting is another important aspect of an aquarium. Find out more about it in the next section.

To learn more about freshwater aquariums, see:

Aquarium Lighting

Make your aquarium a non-stressful environment for the fish.
Make your aquarium a non-stressful environment for the fish.
©2007 Publications International, Ltd.

Aquarium lighting makes it possible to fully appreciate the beauty of the fish and the aquascaping in the tank. It also provides necessary illumination if you choose to use live plants.

Assuming the location for the tank has been chosen carefully, tank lighting will allow you to control the amount and duration of light the aquarium receives. For all these reasons, the aquarium hood, which contains the light fixture, is an essential component.


The hood fulfills several functions in addition to providing illumination for the tank. It minimizes the evaporation of tank water and it prevents dust and other items from entering the tank easily.

It also stops most fish from jumping out of the tank. Some fish, however, manage to jump through even very small spaces in the hood, in places where equipment is set up.

The back of most hoods contains precut openings for filters and heaters. These openings can be pushed or cut out as needed. If they are larger than the items they are intended for, a fish may find its way through the extra space. As a general rule, this only happens if the fish is already under considerable stress.

Many hoods come equipped to accept incandescent light bulbs. These can be adequate for illuminating the tank, but they do have drawbacks.

Incandescent bulbs generate quite a bit of heat, only adding to the problem of keeping aquariums from overheating during the warmer months. The bulbs don't last very long and can use a lot of electricity, especially in a larger tank where several of them are required.

For these reasons, a hood with a fluorescent fixture already installed or a kit to convert the hood to fluorescent lighting should be used. Despite their higher initial cost, there are several advantages to fluorescent tubes.

They run cooler, last much longer, and use much less energy than incandescent bulbs. They are also able to supply enough light to successfully grow live plants.

Many hoods, however, do not have room for more than one fluorescent tube, which may not be enough to keep live plants. The usual recommendation for lighting is three watts of light for each gallon of water. Although inexact, this guideline is a good indicator of the minimum wattage needed.

A second light fixture will often be necessary. The exact requirements of your aquarium will depend on its size, the number and type of plants it has, and the number and type of fish it has. It is best to consult your regular dealer about this so you can tailor the lighting to your exact needs.

There are actually two concerns with light: intensity and duration. If there is insufficient intensity, leaving the lights on longer will not help. One sign of inadequate light is that plants will have long stems but few leaves.

In a properly lit tank, the lights need only be on for eight to ten hours. It should also be noted that some fish do not like very bright light, and all fish need to have regular periods of darkness, just as they do in nature.

Go to the next page to learn about aquarium plants.

To learn more about freshwater aquariums, see:

Aquarium Plants

Fish feel more secure when there are plants in which to hide.
Fish feel more secure when there are plants in which to hide.
©2007 Publications International, Ltd.

Live plants can add beauty to any aquarium and are good for the fish as well.

Fish feel more secure when there are plants to hide in. Some fish will spawn among plants, and vegetarian species will eat plants. Because you are not likely to want your aquarium plants eaten, you will either have to avoid vegetarian species or use plastic plants instead.


Many species of live plants will do well in an aquarium, but some do better than others depending on the water chemistry and the amount of light.

Do not use house plants in an aquarium. They will not last long and will contribute to water quality problems as they begin to decay.

Unfortunately, some dealers are not familiar enough with live plants to always know whether the plants they carry are truly aquatic species or not. A good book on aquarium plants is very helpful in this regard and will also provide extensive information on the care and maintenance of plants.

Live plants compete with algae for nutrients in the water, and therefore limit their growth. Many hobbyists think algae are unattractive, but they are a natural part of any aquatic ecosystem and can provide food for some species of fish.

Problems with these single-celled plants begin when they multiply too rapidly, which is usually the result of too many nutrients in the water and too much light being available. Partial water changes and a reduction in the number of hours the tank lights are on usually control excess algae. If the tank is located where it receives sunlight, it can be impossible to control algae growth.

Plastic plants are preferred by many hobbyists. They can be very realistic in appearance, and they largely eliminate the need to worry about having enough light.

In addition, some species of fish are stressed by intense illumination. They can be uncomfortable in tanks with the bright lighting required for plant growth. Artificial plants make it much easier to decorate their tanks suitably.

Learn how to test your aquarium water with a simple kit on the next page.

To learn more about freshwater aquariums, see:

Aquarium Water Test Kits

Knowing the pH level of your aquarium water is important.
Knowing the pH level of your aquarium water is important.
©2007 Publications International, Ltd.

Aquarium water test kits are an important item for hobbyists to keep on hand. The water you pour into the tank has several characteristics that you need to consider. These include the pH, how hard or soft it is, and any chemicals that may have been added that could endanger the fish.

In addition, the fish introduce other compounds into the water that will slowly reduce the water quality. Looking at the water tells you nothing about its chemistry and very little about its quality.


Monitoring water chemistry and water quality requires test kits. It is surprising how many people will spend a substantial amount of money for an aquarium setup but balk at spending a few extra dollars for three basic test kits -- ammonia, nitrite, and pH.

There are actually many more types of test kits available, but these three are the minimum needed to check the water. Other kits test for nitrate, copper, chlorine, dissolved oxygen, and more.

There are differences in test kits that you will want to take into consideration when choosing them. Some kits have liquid components, or reagents, that test the water, and others have dry reagents. As a rule, dry reagent kits have a longer shelf life and are more reliable than kits with liquid reagents.

However, all test kits have a limited shelf life, so you want to buy only kits that have expiration dates for the reagents clearly marked either on the box or somewhere on the packaging inside.

You will find that some kits are easier to use than others. In particular, be aware that most kits require you to compare the color of the water sample being tested with a set of standard colors in order to judge the results of the test.

Ideally, because you will be holding the vial with the test sample up to the light to see the color, the set of standard colors should be viewed the same way. Unfortunately, most test kits use a printed color chart, which forces you to compare a sample illuminated by direct light with a chart using reflected light, which can make accurate comparison difficult.

The ammonia and nitrite test kits are the most critical. The kits are used both to monitor the rise and fall of these compounds, indicating the completion of the initial nitrogen cycle, and as a regular check on the water quality.

If any of your fish become sick and upon checking the water you discover that either ammonia or nitrite is higher than it should be, you will have a clue as to the source of the problem.

Learn more about aquarium water pH levels on the next page.

To learn more about freshwater aquariums, see:

Aquarium Water pH Levels

Fish are picky about the water in which they swim.
Fish are picky about the water in which they swim.
© Peter Harrison

Understanding aquarium water pH levels is important, not only to have an idea of what it is but also to compare later with the tank water to judge how things are functioning in the tank. A simple aquarium water test kit will provide a reasonably accurate reading of the pH.

The pH scale runs from 0 to 14, and for monitoring aquarium water, you need to work in increments of tenths.


A pH value of 7 is the midpoint, which means the water is neutral. As the pH values go down from this midpoint, the water is increasingly acidic; as the value goes up from the midpoint, the water is increasingly alkaline.

A change of one whole number (i.e., 7.5 to 6.5) actually represents a change in acidity or alkalinity of 100 times.

Many aquarium fish that originate from South America prefer softer, more acidic water, whereas fish from East Africa do best in hard, alkaline water. These are just two examples.

Unless you intend to breed a species that is very particular about water chemistry, you will find that the stability of the pH in an aquarium is far more important than the exact value.

Large, rapid changes in pH are often fatal to fish. Any change greater than 0.2 in a 24-hour period will cause physical stress for most fish.

There are products on the market that can alter the pH up or down. However, changing the pH that quickly can cause the very problems you're trying to avoid, and the chemicals provide only a temporary solution. Once you use them, it can be difficult to maintain the proper pH without them. You would also have to store a supply of water with the altered pH for regular and emergency water changes.

Most fish will do fine in a broad range of values starting as low as 6.5 and going up to 8.0. Some species will do better at even higher or lower values than these, but for all practical purposes, it is best to allow the pH to settle at a value and simply leave it there.

As a natural part of the biological processes in an aquatic environment, the pH in the tank will become increasingly acidic over time. The change is very gradual, though, and so poses no real threat to the fish.

Eventually, the pH would drop low enough to cause problems, but the partial water changes you'll do as a part of regular tank maintenance will keep that from happening.

Learn about the differences between hard and soft aquarium water in the next section.

To learn more about freshwater aquariums, see:

Hard and Soft Aquarium Water

An aquarium is a creative endeavor but has a technical side. You'll need to know, for example, whether your water is hard or soft.
An aquarium is a creative endeavor but has a technical side. You'll need to know, for example, whether your water is hard or soft.
©2007 Publications International, Ltd.

You should know if your tap water is hard or soft so you can adjust it if necessary for your aquarium. Hard water has a high content of certain minerals -- magnesium, calcium and iron salts -- and soft water does not.

The biggest concern with tap water, though, is what the city water department puts in it. Most municipal water companies add chlorine or chloramine to the water to kill certain bacteria that are harmful to people. Unfortunately, these chemicals are themselves harmful to fish and must be removed from the water.


Every pet store has a selection of chemicals that will easily dechlorinate the water. For dealing with chloramine, however, you need something a little different.

Chloramine is a combination of chlorine and ammonia. When a normal dechlorinator is used at double the recommended amount, it will break the bond between these two compounds, neutralizing the chlorine but releasing the ammonia. The added ammonia may be more than the nitrifying bacteria in your tank's biological filter can handle.

The only way to handle this problem is to use a one-step water conditioner designed to handle chloramine. This product will break the bond between chlorine and ammonia and neutralize both.

The easiest way to determine what your local water company is adding to the water is to call them and ask. Be aware, however, that cities using chlorine may suddenly switch to chloramine, which could cause problems if your tank doesn't have effective biological filtration or is overcrowded.

If you have well water, you might consider having it checked by a professional laboratory. Although there will be no chlorine or chloramine in the water, it may contain high levels of iron or other substances that could prove harmful to your fish.

In areas with farming, well water sometimes contains high levels of nitrates, which only add to the levels already in the tank from the nitrogen cycle. These nitrates come from the fertilizers used on farm crops.

Check out the next page to learn about aquarium aquascaping.

To learn more about freshwater aquariums, see:

Aquarium Aquascaping

There are lots of different choices when it comes to aquascaping your aquarium.
There are lots of different choices when it comes to aquascaping your aquarium.
©2007 Publications International, Ltd.

The first consideration when decorating an aquarium, or aquarium aquascaping, is the gravel.

The size of the individual pieces of gravel is particularly important if the tank has an undergravel filter. If the gravel is too large, there won't be as much total surface area for the nitrifying bacteria. On the other hand, if the gravel is too small, it will clog with particles easily and restrict the flow of water through the gravel bed.


The best gravel sizes are #2 or #3, which are two and three millimeters in diameter respectively.

Although the color of gravel is a matter of personal choice, neutral colors are more natural and do not compete with the fish for attention. They also help to make the fish more comfortable.

You may notice that many fish are dark on top and lighter on the bottom. This is a form of camouflage called countershading. The fish will be less visible to predators when viewed from above against the dark bottom of a stream or pond, or when viewed from below against the light color of the sky. For this reason, fish feel more secure over dark gravel.

While you are contouring the gravel, you can use rocks and cured pieces of driftwood to create terraces, ledges, and caves. These will add visual interest while providing shelter and hiding places for the fish.

Choose rocks that are not going to alter the chemistry of the water. Your local aquarium store will have a good selection of rocks that are safe for the tank, along with driftwood that has been properly cured. Curing driftwood yourself is a slow, tedious task. Incompletely cured driftwood can pollute the water and kill the fish.

Neutral colors make fish feel more comfortable in their aquarium home.
Neutral colors make fish feel more comfortable in their aquarium home.
© Educational Images

Do not use corals or shells for decorations. These items not only look out of place in a freshwater aquarium but they can also make the water harder and more alkaline than it normally would be. Also, avoid rocks that have rough surfaces or sharp edges that could injure the fish.

It is very important that all rockwork be stable. The base of any large rocks should rest securely on the tank bottom, not on the surface of the gravel bed. Should the rocks fall, the aquarium glass could crack or fish could be injured.

Learn about a few remaining aquarium items in our final section.

To learn more about freshwater aquariums, see:

Other Aquarium Items

Nets are just one of many items that are important to proper fish care.
Nets are just one of many items that are important to proper fish care.
©2007 Publications International, Ltd.

There is a large variety of other aquarium items and accessories available for aquarists to choose from, but only some are absolutely necessary.

You will want to have enough air line tubing to run between the air pump and the air stones, as well as some extra air stones. Over time, air stones begin to clog, which reduces their efficiency and causes unnecessary wear on the air pump.


You should also have an extra set of replacement diaphragms on hand for the air pump. If not, your dealer can replace them for you when they wear out.

Some hobbyists like to be prepared for larger problems. If you are willing to make the investment, a back-up pump and even an extra heater or filter provide insurance against equipment failure.

A gang valve is very useful for distributing and regulating air flow. Air from the pump goes first to the gang valve and then separately to each air stone. The air stones can then be regulated individually, and if the pump puts out more air than you need, excess air can be routed through an unused valve.

Routing the surplus air through an air stone reduces any noise coming from this line. Bleeding off excess air keeps the diaphragms in the pump from wearing out too quickly.

If the air pump is going to sit on the floor or on a shelf that is below the waterline in the tank, a one-way check valve should be used in the line between the pump and the gang valve. Should the electricity go off and the diaphragms stop in the wrong position, water could be siphoned from the tank through the air lines into the pump, ruining it.

A check valve will prevent the water from reaching the pump. If the pump has more than one outlet, there should be a check valve for each line.

You can use several different items for keeping the inside of the front glass free from algae. A sponge or plastic pad on a long handle, a pair of magnets -- one with a cleaning pad and the other with a felt pad -- or a long-handled plastic scraper will make it easy to remove algae.

A good-quality, one-step water conditioner should always be available for regular water changes as well as any emergencies, such as having to set up a hospital tank for a sick fish.

A supply of mechanical filtering material and granular activated carbon should be on hand for regular maintenance. If the filter uses special seals or O-rings, an extra set of these should be kept available.

Buy at least two nets. It is easier to catch fish in the tank by using one net to guide or force the fish toward the second net, and it's also a good deal less stressful for the fish.

One of the best investments you can make is to purchase a hydro-vacuum to help with tank maintenance. These gravel cleaners are inexpensive, but they're essential tools for keeping the tank clean and healthy.

Finally, you will need a bucket or two, paper towels, and glass cleaner. There are many other accessories that you can buy, but it is better to get the tank up and running for a while first. Then you will be able to determine which, if any, of these other items you would find useful.

To learn more about freshwater aquariums, see: