Water filtration is an important part of fish care, as water must be kept clean for fish to thrive. Filters will aerate water and help keep ponds and aquariums clean. Filters must also be maintained to function properly. They should be cleaned regularly and changed when necessary.
How often a fish filter should be changed depends on the size of the pond or tank, the number of fish kept, the size and type of the filter and the number of filters used in the tank.
Types of Filtration
Water filtration can be categorized as biological, mechanical or chemical. Chemical filtration uses activated carbon to absorb chemicals from the water. The carbon filter must be changed about every two weeks.
A large tank will best be maintained through mechanical filtering. This takes place with a power filter. Pads or cartridges of a power filter need no changing until they begin to deteriorate, which usually takes about a month. Pads can be rinsed in the interim if tank water appears cloudy.
Biological filtration uses positive bacteria to remove ammonia and nitrite from the aquarium water. It takes approximately five to six weeks for helpful bacteria to generate in the filter material. The filter should not be cleaned or changed before this build up is generated.
A good measure to determine if a filter sponge needs changing is to squeeze it. If it doesn't return to its original form within seconds, it needs to be replaced. Restricted water flow or cloudy water can also indicate that a change is necessary.
Avoid purchasing filters not produced by recognized industry manufacturers as they may not be the best quality and will not last very long.