The Importance of Regular Water Changes
Regular water changes are an indispensable key in maintaining aquarium water quality. This holds true for all aquariums, even those equipped with the most advanced, expensive, and effective filtration systems available. Regular water changes will also relieve your filtration system of a good deal of work, thereby increasing its overall efficiency.
The frequency of the water changes and the amount of water that should be replaced each time will vary greatly depending upon the size of the aquarium, the number and types of creatures that are kept within, and the stage of the nitrogen cycle that is in progress at the time.
Full Tanks Versus Lightly Stocked Tanks
Obviously, heavily stocked tanks or those with large animals that produce a good deal of waste will generally require more frequent changes than will lightly stocked tanks housing live rock, plants, and small animals.
Water changes may also be required more frequently during the early stages of the establishment of your aquarium, before large populations of beneficial nitrogenous bacteria have become fully established.
Invertebrates, both freshwater and marine, are nearly always more sensitive to water quality than are most fish. Unfortunately, invertebrates do not usually make it obvious that they are in distress due to poor water quality. Therefore, it is important that you observe them carefully and always maintain your water within safe parameters.
In all cases, however, water changes are the most effective means of removing ammonia and other harmful nitrogenous wastes and in maintaining the overall quality of the water and, therefore, the health of your pets. It is especially important to remember that organic debris, such as animal waste, uneaten food, and decaying plant material will release carbon dioxide during decomposition. This will buffer the water, lowering the pH, and, eventually, compromising the health of your pets.
The best way to remove water from the aquarium during a water change is to use a “gravel cleaner” attached to a siphon. These are available in a variety of models, including ones with very long hoses that attach to a sink and utilize pressure from the sink to draw water from the aquarium. The end of the siphon is thrust into the substrate, where it draws out trapped detritus while leaving the substrate in place.
Such cleaners are not practical in heavily planted aquariums where the entire substrate is covered by living plants. In such situations, merely siphoning water from directly above the substrate should suffice. Do not use a siphon that expels aquarium water into a kitchen sink or in other areas where food is prepared. Always drain water into a utility sink or out of a door or window.
Except for unique situations, such as during the early stages of the establishment of your aquarium, or when you are keeping large animals or large numbers of animals in a tank, a monthly change of 20 to 25 percent of the aquarium's water should be sufficient to maintain water quality. A more effective schedule would be to change 10 percent each week, but this is not always practical.
Added Water After Water Change
The water to be added to the aquarium after the water change should be prepared beforehand and aerated overnight, if possible. Although chlorine will generally evaporate from water within 24 hours, it is a good idea to use commercially available preparations to be sure that all chlorine and chloromine is removed from the water before it is added to your aquarium. Most preparations available today act instantly and are harmless to fish and invertebrates.
Water lost through evaporation from a marine aquarium should be replenished with freshwater, not saltwater, because sea salts are not lost during evaporation. Adding more saltwater would raise the overall salinity of the aquarium's water. Water removed from a marine aquarium during a water change should, however, be replaced with saltwater of the same specific gravity.
The makeup water should be poured slowly into your tank or onto a sheet of glass held on the water's surface, so as not to disturb the substrate or your pets. The water added to the aquarium after a water change should, of course, be of approximately the same temperature as that in the aquarium.
If you are keeping a marine aquarium, be sure to add trace elements to the replacement water as per the schedule recommended by the manufacturer.