Partial water changes are done to maintain the water quality
s. The amount removed must be limited in order to maintain an adequate amount of the helpful bacteria
in the tank
for maintaining the nitrogen cycle
. Large water changes also make larger changes in the pH
of the water more likely. Sudden changes in the quality of the water may be stressful to the fish and can cause disease and death.
Old water is removed while cleaning the gravel (if gravel
is being used) with a gravel vacuum
. The new water must be dechlorinate
d prior to being placed in the aquarium
. Efforts are usually made to make the temperature
of the water added identical to the temperature of the water in the tank. At times slightly cool
er water is used to imitate a rainstorm
. This induces breeding behavior in some fish. Larger than usual partial water changes may also be done to induce breeding behavior in somefish ... "Flash flood or rainy season, better breed quick!" said one fish to the other...
If the tank
is a saltwater tank
the saline ratio
is also matched. At times chemical
s are used to match the pH
of the new water to the older water
. If you dislike adding excessive chemicals to your tank
and if your fish require a pH either more acid or more alkaline than your tap water then smaller and more frequent partial water changes are even more important.