Aquarium Filters Functions and Types

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Choosing aquarium filters is just as important as choosing the type of tank and fish that you want. The filter is the life support system for any aquarium and fish will not survive for long without a filter. There are three primary functions for a filter system:

• Biological filtration
• Mechanical filtration
• Chemical filtration
Filter types can be further broken down into:
• Internal and external
• Air powered or power filters

Popular types include air powered sponge filters, hang-on power filters, and canister filters. Canister filters are by far the most popular method of filtering any aquarium these days, as they are reliable, quiet and efficient, while requiring maintenance less often than other filters.

Whatever you choose, aquarium filters should always be rated for the size of the aquarium it is filtering. It is always okay to go with a filter rated for a tank a little larger than the one you have, but never go with a filter that is rated for a tank that is smaller!
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Aquarium Filters

Before you select a filter, take the time to review your options and think about the specific needs of your tank. There are three primary functions for a filter system:
  • Biological filtration – The most important and absolutely necessary function of an aquarium filter system is for biological filtration. This is the process of converting the toxic ammonia produced by fish into relatively harmless nitrate.
  • Mechanical filtration – This process physically removes debris such as fish waste, leftover fish food and other gunk from the tank water.
  • Chemical filtration – Depending on what filter media you have in your filter. Those filters with activated carbon pads are capable of removing certain chemicals from the water.

How to Choose a Filter

All filters have a set of specifications on them, provided by the manufacturers. Other things to consider include:
  • Recommended tank size – This is the tank size recommended by the manufacturer to use with their filter. For example, most of them say "up to 20 gallon” or "up to 30 gallon”. It is the maximum size of tank that the manufacturers suggest to use with their filter. A heavily stocked tank with more or bigger fish will require more filtration than a lightly stocked tank of the same size.
  • Gallon Per Hour (GPH) – This is the flow rate of the water. The faster the water goes through the filter, the more efficient the biological filtration is. If you are using a power filter, the recommended GPH should usually be high enough to go through your entire tank water five to seven times each hour. Canister filters are on a different level because they have a lot more filter media in them, and they should be fine with just enough power to go through all of your tank water three times per hour.
Without a filtration system for your water, it would almost be impossible to keep tropical fish as pets.