Water filters are very important and vital for freshwater aquariums, ponds or fish tanks.
They help create suitable conditions for fish and other inhabitants.
They extend the period for which water can be used before replacement.
Fish and aquatic plants need special conditions to survive in freshwater aquariums.
These conditions cannot be met perfectly but you can definitely take certain measures to enable the inhabitants to survive and nourish.
These filters remove the waste from water using different methodologies and create suitable conditions within the freshwater aquarium.
In fish's real habitats there are lots of plants that help in maintaining the aquatic ecosystem whereas, the aquarium is not big enough to accommodate lots of different plants.
This makes it necessary to have some means to fulfill their purpose artificially.
Water pollutants also depend upon the type of inhabitants.
For example Goldfish, one of the hobbyists' favorite, produces a lot of waste.
Three main types of filters are: •Biological, •Chemical and •Mechanical Utilizing all three types of filters will help you out in the best way possible.
These days, the filters installed in freshwater aquariums contain all three kinds of these.
Here is a short list of most commonly used biological filters in freshwater aquariums: Sponge filters: They work by passing water through a porous sponge at which bacteria are allowed to grow and nourish.
You can say that they are purely biological filters.
The sponge shouldn't be cleaned or dried because this will kill the nitrifying bacteria.
Undergravel filters: They are also biological in nature.
They just take water from the bottom side of freshwater aquarium and then take them up through the gravel layer.
A reverse undergravel filter works the other way i.
e.
it takes water from top and brings to bottom side through gravel.
Canister filters: They consist of a container or basket inside the filter where various filter media are stored.
These baskets are filled with some biological material like biological balls that will help grow bacteria colony.
Once this colony is established, you wont need to remove the filter or clean it.
There are several different kind of freshwater aquarium filters in the market.
There are several manufacturers producing these filters.
I tried to give you a basic idea of how to select the filter.
You definitely need to consider the scenario you are in and then decide for the type of filter.