By Donna M. Recktenwalt
One fact that is mentioned in almost every published aquatic resource, regardless of species, water type or tank size, is the need for regular partial water changes. Unfortunately, despite the fact that water changes are a good and useful thing to do, many people don’t do them.
Why not?
Because it’s messy; it’s sometimes smelly; it takes too much time. Besides, the plants and the fish seem fine, so why bother?
Except …
Regular water changes help prevent algae blooms. Algae feed on nitrates and phosphates, which do the fish no good. Change the water, the algae won’t have as much source of nutrition, and the fish will be happier.
Regular water changes help prevent fish disease. Fish having to deal with high amounts of ammonia and nitrates are stressed; stressed fish are more susceptible to disease.
Regular partial water changes replenish trace minerals and oxygen that become depleted over time due to filtering, and to normal biological processes.
Regular partial water changes allow young fish to reach larger sizes more quickly.
And the influx of fresh water often will stimulate spawning.
When you should change the water depends on many factors: how many tanks do you have? How much conditioned water do you have on hand at a given time? How heavy is the fish load in your tanks? What type of filtering are you using? Do you use live plants?
In general, the water should be clear, light colored (unless you’re using peat, when it may turn quite dark), and it should smell fresh. If the water is cloudy or dark or has an odd odor, it’s time to change it. If the fish or the plants appear distressed, or the fish are showing signs of illness, it’s past time to change the water. If the filter hasn’t been operating properly, or if the intake tubes are slimy and clogged, it’s time to change the water and clean the equipment.
By doing regular partial water changes, you should almost never have to face doing a forced water change, because conditions in your tanks will remain fairly stable.
How Often Should You Change the Water?
Most recommendations for water changes are in the range of 10-30% every week or two, although the exact requirements will vary with your fish and your setup. Some aquarists perform more extensive water changes less frequently, others perform smaller changes more often. Each aquarist has to determine what best suits their needs and available time. Of course, if you have a central water system, the water is being changed at a constant, fairly regular rate, so the question is unimportant.
This aquarist vacuums the gravel and changes 25-30% of the water on a more or less weekly basis. At the same time, the foam filter pads are rinsed out and any clogged or overly slimy intake and air lines cleaned. The used water is recycled into the garden, both in- and outdoors. Whenever possible, the replacement water consists of 2 parts conditioned tap water (pH about 7.0) to 1 part collected rainwater. Fish that prefer harder water receive straight tap water. Tap water is conditioned by adding a dechlorinating agent and allowing it to sit overnight.
There are various methods for handling the conditioned and waste water, depending on your facility and tank arrangement. For those in basement fishrooms, placing a water reservoir container as high in the room as possible to allow for gravity feed may be a good answer; also, waste water can often be channeled into a floor drain for disposal. Alternatively, you can place the reservoir on the floor and use a small submersible sump pump to deliver the conditioned water.
Rainwater is usually collected from downspouts and channeled into a reservoir in a convenient location. For some, this means outside, with a hose run into the [usually basement] fishroom, for others, the holding tank may be in the basement itself. Reservoirs should be of sufficient size to supply your needs, and be of an easy to clean, non-rusting material that is not subject to breakage, such as heavy-duty vinyl trash cans, or plastic, poly, or fiberglass drums or containers. For those with less room and/or small numbers of tanks, used plastic milk jugs work just fine for water conditioning, although they do mean more carrying. A 3-5 gallon pail is a convenient size for waste water transport.
“The best water one can have is the easiest water,” reminds Charles Harrison. “Changing it often is the best method of conditioning it. People who treat it in … many ways often don’t change it often enough. Use your water as it is, let it bubble overnight to lower the pH and remove the Chlorine, and keep your tank water as fresh as possible.”
– G.C.K.A. Newsletter, October 1999