Freshwater

Popular mechanical filter types include
Canisters
Power filters
Corner filters
Mechanical filters come in many different sizes to accommodate the many
different tank sizes. When you go shopping for filters, we suggest purchasing
Penguin, Ehime, or Whisper products, because in our opinion they are the
cream of the crop.
A good filter cycles your tank’s water volume at least eight times per hour.
Mechanical filters are rated on the number of gallons of water that flow
through them every hour. If you look carefully at a filter box, you can usually
find a GPH (gallons per hour) rating. Manufacturers generally indicate on the
label which size tank the filter is designed for.
If you have a tank larger than 10 gallons, you may want to have more than
one filter running even if your filter covers all of the requirements for taking
care of your water. You could for example have two power filters, or a canister
filter and a power filter. There is nothing wrong with mixing two different
types of filtration system, or having multiples of one type. As a general rule,
we always have at least two filtration systems on each of our tanks just in
case one fails.
Biological filtration
Chapter 6: Equipment and Other Technical Stuff
The main purpose of biological filtration is to provide a home for the bacteria
that changes ammonia into nitrates and then nitrates. The function of nitrifying
bacteria is to convert deadly ammonia (produced by fish waste) and food
debris into less harmful nitrites, and then into even less harmful nitrates
which can be removed with water changes. This amazing biological purification
process is also known as detoxification or the nitrogen cycle. Chapter 14
talks a lot more about it.
The bacteria are everywhere naturally (air and water) in small amounts. By
adding fish and food, the bacteria have the nutrition required to establish a
larger colony. The filter medium provides the perfect “nesting” place for them
to multiply.
Large filters don’t necessarily mean better biological filtration. What counts
is the amount of surface area on the medium. The larger the total surface
area of the medium, the more bacteria your system and fish have to use in
the fight for good water quality.
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