Understanding Filtration - pt.3
OUTSIDE THE AQUARIUM FILTERS
These filters have a myriad of advantages over inside the aquarium filters. Because they are located outside the aquarium, the entire inside of the aquarium becomes “livable” space for fish, plants and invertebrates. Again because the filters are not integrated inside the aquarium they can be made large and powerful thus substantially increasing the available bio-load for the aquarium size. The minor drawback is that the aquarium water is removed from the aquarium and sent to an external chamber (filter) so the possibility, even minimal, is that it could leak and water could end up someplace other than it should be.
External Power Filters
These filters are currently the most widely used due to efficient filtration, simplicity of use, and reasonable cost. They hang on the back rim of the tank, with an uptake tube that extends down into the tank. Water is drawn up the uptake tube where it flows into a chamber where media filters the water. Various designs exist, and they usually manage to perform the three types of filtration (biological, mechanical and chemical) efficiently. The main difference found between the many brands and models is how much water is moved through the unit per hour and the ease of media cleaning and changing. For efficient filtration of an aquarium, turning the tank’s volume (in gallons) over 3 to seven times and hour is preferable. This means that for a twenty gallon tank, a filter that pushes 60 to 140 gallons per hour through it is ideal. As the media clogs with detritus, the optimum flow rate may decline, so it generally good to err toward the higher end of flow rates on a filter.
Canister Filters
Canister filters are also external power filters, but generally sit under the aquarium due to their size and weight. They push or pull water through a set of media outside the tank in the filter housing. Canisters are a little different, though, in that they filter the water in a completely sealed, pressurized container. Water is again pulled into the unit through an uptake tube and passes through various media before being expelled to the aquarium again. Canister filters employ powerful pumps to move the water, so the flow rates are often in excess of what might be found in an external hang on power filter.
The main benefit of canister filtration is that the filter itself is virtually invisible, since the bulk of it resides beneath the aquarium, in the stand.Additionally, the powerful water movement and exceptionally large space for filtration media allows these filters to be used on large tanks or small tanks with large bio-loads.With quick disconnecting
