Aquarium Fish

Water Quality: How to Maintain It

posted: 05/15/12

Maintaining a healthy aquarium has gotten much easier over the past twenty years. With improvements in filtration, lighting, test kits, and increased knowledge of fish species it has never been easier to have a successful aquarium. But despite all these improvements, maintaining good water quality can still be a challenge for many aquarists. Maintaining good water quality is the single most important thing that an aquarium owner can do to ensure the health of their fish. Poor water quality is probably responsible for more aquarium fish deaths than any other factor. This article will cover the basics of maintaining water quality in your tank. For more detailed information about water chemistry see the article, Water Chemistry: The Basics.

Setting up the tank correctly

Many problems with water quality start before we even add water to the fish tank. Most new tanks are well made and do not contain toxic materials in the caulk or general construction. The problems usually arise from the substrate and decorations that are added to the water. If you use gravel, rocks and wood from your yard or garden shop, be aware that you can be bringing contaminants into your tank. A common problem is when people put rocks or gravel of unknown origin into their tanks and the rocks contain limestone. The limestone will make the water more alkaline and the aquarium owner will constantly struggle with maintaining the proper pH in their tank. Setting up the tank with clean appropriate substrate, wood and rock is the first step in maintaining water quality.

Testing the water

If we do not know what the problem is we cannot fix it. This is especially true with aquarium water. A test kit that analyzes the level of pH, water hardness, nitrate, nitrite, and ammonia is probably the minimum that is required. Weekly monitoring of all of these parameters is going to be required initially before the tank has a chance to mature and become a stable environment. Periodic checking, especially if some of your fish develop health problems, is also a good idea.

One of the best uses of your test kit is to test the water from your faucet before you set up your tank. If your tap water is very hard and has a pH of 8 or is very soft and acidic with a pH of 6 you have two choices. You can either constantly treat and adjust the water during weekly water changes or you can choose species of fish that are suitable for your water conditions. If you choose the appropriate species of fish your water maintenance will be much easier.

Water changes

Weekly water changes are probably the most important part of maintaining good water quality. Weekly water changes of around 15 to 20 percent of the total water volume will correct many potential problems in water quality. The water changes will bring fresh mineral rich water into the tank. The fish, plants and bacteria use up the trace minerals in the water and by adding new water weekly you replace these minerals. By removing water you reduce the amount of nitrate and ammonia that builds up in the water as well. Weekly water changes also help remove other toxins or pollutants that can build up in the tank. If a siphon with a gravel cleaner is used the gravel can be cleaned and uneaten food and fish and plant waste can also be removed. This keeps the ammonia levels down and the water cleaner. (If you have an under gravel filter or a filter system that does not have a biological filter you may not want to disrupt the good bacteria by over cleaning the gravel).

Remember that most tropical fish live in environments where currents or rainfall regularly bring fresh water and remove waste. By providing weekly water changes we help to simulate this natural and much needed requirement. An important note about water changes is to make sure the total does not exceed a third of the water volume. It is also important that the water that is added is the correct pH and temperature and free of chlorine etc.

Live plants

Whether or not to have live plants in an aquarium is often a personal choice and many aquariums do very well without ever having a live plant in them. However, my personal preference is to have live plants in a tank and I feel that they offer many advantages. While some live plants can be difficult to grow and may initially require a little more maintenance, the benefits to water quality and fish health are well worth it. Plants are great at absorbing carbon dioxide and nitrates and provide shelter and security for the fish. Because they compete with algae for nutrients they can also help reduce algae growth. Live plants also enhance the appearance and provide a much more natural environment for the fish. By improving water quality and reducing stress, live plants are a great way to improve your fish's health. Adding live plants does not reduce the need for weekly waters changes. When selecting live plants make sure to choose species that are truly submersible and that are suitable for your specific water type and fish species.

Biological filtration

Biological filtration is the action of bacteria in the tank breaking down dangerous ammonia to nitrites and then the nitrites to the less toxic nitrates. Today most good new filters provide a separate area or wheel for the specific task of growing these necessary bacteria. These good nitrifying bacteria will grow in other places in the tank and on other filter media but not with as great a numbers. It is hard to argue with the success of these new filters and their ease and success in providing high quality filtration. Regardless of which system you use to provide biological filtration, it is a very important part of maintaining the water quality. Remember that it takes weeks to properly grow the bacteria in a biological filter, so if you are setting up a new tank, wait several weeks before adding fish. At the same time be careful not to damage your existing biological filter with antibiotics, chemicals or over cleaning.

Some aquarium owners may look at water maintenance as an unpleasant chore, but it does not have to be. Running a water test and doing a partial water change is extremely important and will only take a few minutes each week and will ensure that your aquarium has cleanest, healthiest water possible.

References and Further Reading

Bailey, M; Burgess, P. Tropical Fishlopaedia. Howell Books. New York, NY; 2000.

Sandford, G. Aquarium Owners Guide. DK Publishing. New York, NY; 1999.

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