The aquarium tank is obviously one of the most important pieces of aquarium equipment you’ll need. The type of aquarium you select will depend on how much you want to spend, how much space you have, and the number and type of fish you plan on putting in it.
Aquariums come in either glass or acrylic, and you can find an assortment of shapes and sizes for both.
Complete Guide to Choosing The Right Aquarium Tank
What is the right size aquarium for you?
The right size of an aquarium depends on many factors: space available, size and number of fish you want to keep, your experience in keeping fish, and your budget. If you are just starting out as a fish keeper, consider either a 30 to 50 gallon aquarium. While smaller tanks are less expensive, as a general rule, the more water you have the easier it is to maintain stable water chemistry and temperature. Stable water conditions generally lead to happier and healthier fish.
In determining where you can put your aquarium don’t forget how much your fully equipped aquarium will weigh. With water, gravel and decorations your tank could easily weigh 12 pounds or more per gallon in size. That’s 240 pounds for a 20 gallon tank. You will need a stable base for your aquarium. You should consider a stand made especially for an aquarium. Furniture is not always made to hold all this weight.
Can I use a glass bowl to keep my fish?
Glass bowls are very inexpensive, and you don’t have to worry about leaks. However, your fish will be happiest and healthiest in an aquarium with a filtration and aeration system. If you decide to keep fish in a glass bowl, choose a fish such as a betta that can breathe at the surface of the water. Remember that without a filtration system you will need to change the water more frequently.
If you have limited space, consider a 2 gallon or 5 gallon plastic aquarium. These units typically come as a starter kit with a filtration system, air pump and light. You can only keep one or two fish in these tanks but they make a nice addition to an office, bedroom or kitchen counter.
Glass Aquarium Tank
A glass aquarium is basically a glass “box” formed using individual pieces of glass held together with heavy plastic top and bottom frames. Silicone is used to seal between the glass pieces and the frame.
The silicone seal not only prevents leaks, but also cushions one piece of glass against the other, which aids in preventing pressure cracks. Glass aquariums are warranted against pressure cracks and leaks.
Glass aquariums are very easy to clean, they don’t scratch as easily as acrylic, and they are generally less expensive than acrylic. They’re made in a wide variety of shapes and sizes – from 5 gallon up to 240 gallons and larger.
Traditionally, glass aquariums came only in square or rectangles. However, new technologies now make bending of glass possible and glass aquariums now come in many new and inviting shapes and sizes.
Glass aquarium tanks are also heavy because the glass used in construction gets thicker as the tank gets larger. This can be a problem if you want a big tank and have weak floors in your home, or if you attempt to move the aquarium.
Glass aquarium tanks can break or shatter and leave you with a lot of dead fish and a huge mess to clean up.
Acrylic Aquarium Tank
Acrylic aquariums are more expensive than glass aquariums, but there are a number of advantages that account for the difference in price. Also, remember that in large aquariums the cost differences between glass and acrylic aquariums are generally much less.
Acrylic aquariums are constructed by using a solvent to weld the seams. This technique assures that an acrylic aquarium will rarely develop a leak. After the aquarium is assembled, the solvent evaporates and the seams become stronger than the acrylic itself. These solvents pose absolutely no danger to the fish within the aquarium. Silicone seams can discolor with age; solvent used in acrylic aquariums does not yellow with age.
Acrylic is 17 times stronger than glass and will flex instead of shatter. This makes it virtually childproof. Because the seams are stronger and the aquarium is more flexible, you can count on having an acrylic aquarium longer. It’s also more clear than glass, and is a better insulator than glass, which means it takes less energy to heat the aquarium. Acrylic weighs half as much as glass, and the bent corners and fewer seams on an acrylic aquarium adds a sleek design to the tank.
One drawback of acrylic aquariums is the tendency for scratches. However, scratches can be removed or lightened from acrylic whereas it is impossible to remove a scratch from glass. Because acrylic aquariums can scratch easily, only those scrubbers that indicate “can be used on acrylic” should be used. Never use an ammonia product when cleaning the outside of an acrylic aquarium because ammonia will crystallize acrylic. Use only a vinegar and water solution for cleaning the outside of an acrylic aquarium.
Because of their design, acrylic aquariums typically come with a full hood and fluorescent fixture that matches the particular aquarium. Therefore, when comparing acrylic aquariums to glass aquariums, remember to figure in the cost of the hood and light if you are considering a glass unit.
Proper lighting is essential for setting up a good aquarium. Every aquarium needs a hood, a glass canopy, and light in order to:
- reduce water evaporation
- help maintain a consistent water temperature
- keep out normal household pollutants
- keep the fish from jumping out (and the cat from jumping in)
- provide necessary light needed for fish
- enhance the colors of the fish and make the aquarium more attractive
- allow for photosynthesis in live plants.
There are two types of lighting available for aquariums: incandescent bulbs and fluorescent tubes. Incandescent bulbs are less expensive than fluorescent tubes. However, they produce more heat and less natural light. Incandescent bulbs are generally found only on 10 – gallon tanks and smaller.
Fluorescent tubes produce a more natural light and much less heat. The fixtures for fluorescent tubes are also much more flexible and will allow you to pick the best type of light for your aquarium.
If you have an aquarium with live plants, you should only use a full spectrum fluorescent bulb. Fluorescent lighting best simulates the light given off by the sun.
Intense lighting, which plants grow best with, can be increased by using bulbs that emit more watts. Heavy plant growth can be achieved by increasing the lighting to 60 watts of fluorescent lighting for every 12 inches of tank length. While more expensive to purchase, fluorescent lights are less expensive to operate.
Unlike warm-blooded humans, fish are ectothermic, meaning they take on the temperature of the surrounding water. Since they can’t maintain the body temperature at a chosen fixed level, the temperature must be maintained through a heater.
Heaters are only necessary if you keep tropical fish rather than marine fish. Coldwater fish like goldfish or koi prefer cooler temperatures (68º – 72º F) and don’t need a heater.
Tropical fish are warm water fish, meaning they like to have their water between 75º F and 79º F. Heaters can help maintain this constant water temperature. Fluctuating water temperatures will cause stress on the fish, which will lead to a number of infections, and even death.
There are two types of aquarium heaters: A “hang-on” style heater and a submersible heater. A “hang-on” style heater provides basic heating of the water. Because the heater is not fully submersed in the water, it is less efficient than a fully submersible heater. Also because “hang-on” style heaters are generally less expensive, they have less precise controls and have fewer operating features.
A submersible heater actually attaches to the inside of the aquarium (typically with suction cups) and the entire heater is positioned under the water. Because the entire heating tube is under the water a submersible heater is more efficient and provides a more consistent temperature.
The rule of thumb when buying a heater is 5 watts for each gallon the aquarium holds. Typically, one heater is sufficient for an aquarium. However, for better heat distribution in larger aquariums, especially tanks more than 36 inches in length, it’s best to have two heaters.
The heaters should be placed at opposite ends of the tank and each should be about half the total required wattage. For example, if you have a 55-gallon aquarium, you will have the best heat distribution is you put a 150-watt heater at each end of your aquarium. If you have a 10-gallon aquarium, one 50-watt heater placed in the center of the aquarium will be enough.
If you use a power filter or a canister filter with only one heater, place the heater at the opposite end of the tank from the filter. This will help ensure good distribution of the heated water.
Aquarium heaters come in different tube lengths to accommodate different height tanks. Because heat rises it is important that you pick the right length heater so that all the water is evenly heated.
While most aquarium heaters can be set to the desired temperature, is always a good idea to buy an aquarium thermometer. The thermometer will help you make sure your heater is functioning properly and maintaining the temperature that is best for your fish.
Thermometers can be either internal or external. Internal thermometers stand upright and are anchored to the glass with a suction cup or they can float. External thermometers are placed on the outside of the aquarium and may be either a dial or liquid crystal design (LCD). External thermometers should be installed on the end of the aquarium opposite the heater and out of direct sunlight.
Helps you maintain the proper temperature for your fish. Floats in the tank or can be attached with a suction cup.
Proper aquarium filtration is critical to keeping happy, healthy fish. A complete filtration system should neutralize ammonia and nitrites, and remove floating debris and contamination from the water. There are three basic filtration methods; mechanical, biological and chemical. Your best fish tank filter system should incorporate all three.
Mechanical filtration is the means by which large particles of excess food and other debris are removed, screened, or skimmed from the water. This is achieved by flowing water through fiber floss, gravel, foam, or some other screening material.
While mechanical filtration uses filters to remove debris, chemical filtration uses activated carbon and ammonia absorbents, such as zeolite, to remove odor, colors and harmful substances, such as ammonia, from the water.
With activated carbon, each piece of carbon is like a little sponge that traps odors, medication residue, and dissolved fish waste. Carbon also removes discoloration in cloudy water. Activated carbon will no longer effectively absorb anything and should be replaced after about 3 or 4 weeks. To test the absorption power of carbon, take a glass of aquarium water on white paper. If the paper looks yellow through the glass, it’s time to change the carbon.
Ammonia can be removed by using a liquid ammonia remover that is placed directly in the water, or ammonia chips, which are put into the filter. However, the use of chemicals to remove ammonia should only be required in unusual cases (such as the start up of a new tank or after a large number of new fish have been added). The primary means of removing ammonia and nitrites should always be your biological filter.
If you need to medicate your aquarium, you’ll need to remove the carbon when treating the sick fish. Otherwise, the carbon will absorb the medication.
A well-established aquarium is a natural ecosystem in which your fish and the beneficial bacteria that naturally occur in an aquarium depend upon each other to live happily and healthy. The result of this interrelationship is commonly referred to as the “Nitrogen Cycle”. Fish eat and produce ammonia as a waste product. Excess food and plant materials also decay and produce ammonia. Beneficial bacteria neutralize the ammonia and produce nitrites, which in turn are neutralized by other beneficial bacteria that produce nitrates. Nitrates in normal levels are harmless to freshwater fish. Thus the natural system in your aquarium converts toxic ammonia into harmless nitrates; all without chemicals or your assistance.
The only thing that you need to do is ensure that you start with a good biological filtration system and that you maintain it. Three conditions are needed in order to establish biological filtration and develop a healthy colony of beneficial bacteria:
There needs to be a place for the bacteria to grow. Bacterial will grow on any porous surface in your tank; on the gravel bed; the replaceable carbon cartridge, wheel, plate or sponge in your power filter; on the bio media in your canister or wet/dry filter; or on the sand in a fluidized bed filter.
The water must be oxygenated. Bacteria needs oxygen to reproduce and grow. An aquarium with proper aeration of the water and good water flow over the beneficial bacteria, will provide sufficient oxygen to maintain the beneficial bacteria. There must be a source of food (ammonia) for the bacteria. Any tank with fish or plants will provide sufficient food. The filtration system must circulate the ammonia carrying water over the beneficial bacteria for them to eat.
What choices do I have in filtration systems for my aquarium? A variety of methods are used to filter an aquarium. All the common methods incorporate all 3 elements of an effective filtration system — mechanical, biological and chemical filtration. The most common methods are:
Undergravel filters in which a slotted plate under the gravel bed is used to provide continuous circulation of the aquarium water (either by introducing a stream of air bubbles into the lift tube or using a powerhead to pump the water) down through the gravel and up through a lift tube back into the tank. Biological filtration occurs as beneficial bacteria living in the gravel neutralize ammonia and nitrites as the water passes through the gravel bed.
Mechanical filtration occurs as the floating particles are forced onto the gravel bed and trapped. When using an undergravel filter it is essential that the gravel be vacuumed thoroughly on a regular basis to remove the trapped particles of food and other waste.
Also trapped waste that accumulates under the filter plate needs to be cleaned periodically. Failure to vacuum the gravel or clean under the filter plate can result in changes to your water chemistry that could be harmful to your fish.
A typical undergravel filter provides no chemical filtration. However, a carbon or zeolite (to remove ammonia) cartridge can be added to the lift tube to provide the needed chemical filtration. These cartridges contain small amounts of carbon or zealot so they need to be changed frequently to be effective.
Power filters have become the most commonly used filtration system in tanks up to 55 gallons. Many hobbyists use a power filter along with an undergravel filter to increase the biological filtration (and thus the number of fish they can keep) in smaller tanks. And many use power filters on even larger tanks in conjunction with canister and other filters.
An external power filter
External power filters is the best choice for combining chemical, mechanical and biological filtration with ease of use. An external power filter hangs on the back of your aquarium and is basically an electric pump that draws water from your aquarium and pumps it through a replaceable filter cartridge that is typically filled with activated carbon. The “carbon cartridge” provides the chemical and mechanical filtration. Biological filtration is accomplished by passing the water over a wheel, sponge, or porous plastic plate that houses the beneficial bacteria.
In some cases the beneficial bacteria live on the replaceable cartridge. You should only use a filter designed in this way with an undergravel filter as other biological filters since replacement of these cartridges removes the beneficial bacteria from your system.
Canister filters are a very effective means of providing a total filtration system. Canister filtration is most typically used on 55-gallon aquariums and larger. While some canister filters are designed to hang on the back of your aquarium, most are designed to be put under the tank and hidden in the aquarium stand. Many believe that an advantage of the canister filter is that it is hidden from sight and thus is more aesthetically pleasing. A major advantage of using a canister filter is the flexibility it gives you in adapting the filter to your other mechanical, biological and chemical filtration needs. These filters are designed to let you determine how much (and what type) of filtration media you want to use.
The only disadvantages are that it requires more hoses and connections than an external power filter and thus is more complicated to set up. Also this type of filter must be disassembled to change media and thus is somewhat more difficult to maintain. Recent designs from the major manufacturers have significantly improved the ease of set up and maintenance of these types of filters.
Other filtration methods have been developed over the past few years. Wet/dry filtration and fluidized bed filters are two of the more popular methods. Both methods can be very effective biological filters. However, they must be used as part of an overall filtration system. Remember, when picking the filtration for your aquarium, you need 3 types of filtration mechanical, biological and chemical, all working together to have the happiest and healthiest fish.
In order to maintain a tank of healthy fish, the water must contain oxygen. The process in which oxygen is introduced into the water is known as aeration.
Fish “breathe” through their gills. They use their gills to extract oxygen from the water that’s then used and converted into carbon dioxide (just like humans) and then discharged back into the water. To ensure that there is sufficient oxygen in the water for the fish to “breathe”, the carbon dioxide needs to be replaced by oxygen. This process is commonly referred to as “gas exchange” and is generally done by aerating the water. A good aeration system is essential to a healthy aquarium.
Aeration is accomplished by breaking the surface of the water or by creating turbulence in the water. It can be accomplished in several ways. Many aquariums are aerated using the turbulence created by the pumping action of a power filter or canister filter and the water falling back into the aquarium. Others use a powerhead with an undergravel filter to pump water across the surface of the tank.
Another common method of aeration is to use an air pump to introduce air bubbles into the water, either with an undergravel filter system or solely with airstones. While both methods involve airstones, in an undergravel filter the introduction of air bubbles into the water creates a current which draws water through the undergravel filter bed and up through a lift tube to the water’s surface. Airstones used without an undergravel filter typically provide supplementary aeration to that provided by a canister or power filter.
Selecting an Air Pump
When selecting an air pump, there are two primary considerations – size and power.
The size of the air pump depends on how much air you need to produce for your aquarium. If you plan to use extra air outlets, such as with action ornaments, bubble walls or decorative air stones, then you should consider a larger air pump. Larger pumps also generally have more outlets, thus alleviating the need for gang valves. When using an air pump with a tall (deep) tank, you should select a larger air pump or an air pump designed for deeper tanks. The deeper the water, the more pressure, and thus the harder the air pump has to work to force air through the airstone and into the water
Airstones are an important part of creating a good aeration system in your tank. Air from the air pump passes through a submerged block of porous material. This breaks up the airflow and produces tiny bubbles, which rise to the surface, breaking the surface tension of water.
Airstones should be routinely changed and cleaned. A clogged air stone will create backpressure, which will shorten the life of the air pump. To test it, simply blow through it. If you can’t easily blow through the air stone, neither can the air pump.
A check valve is a small simple device that is attached to the airline tubing, allowing water to flow in only one direction. It prevents water from siphoning out of the aquarium and flowing backwards into the air pump in the event of an electric power failure.
A gang valve allows the airflow of one air pump to be divided out into many air lines (for example, one for an undergravel filter, one for an action ornament, one for an air stone, etc.). Brass valves are slightly more expensive because they last longer, are easier to adjust and are less prone to air leaks.
The airflow of each valve can be adjusted individually on the gang valve. These generally come in two, three, four, and five-way valves. By using a gang valve, you don’t need to have a separate air pump for each filter, air stone, action ornament, etc.
Airline tubing is the clear plastic flexible tubing that runs air from the air pump to the aquarium. It’s always a good idea to buy extra airline tubing because you’ll need it to hook up any airstones, underground filters or action ornaments.
Tubing comes in both extruded plastic and silicon tubing. Silicone tubing is slightly more expensive because it lasts longer and is more flexible. Extruded plastic tubing is stiffer and tends to yellow and crack with age.