Canister filters Canister filters have hoses that connect them to the tank and valves to isolate intake and return in each hose. They provide mechanical and chemical filtration, but not all models perform biological filtration. They are placed in a stand under the fish tank. Most canister filters be used in tanks with capacities from 10 to over 100 gallons. They are fairly efficient, operate quietly, and run with less frequent cleaning. Power filters Power filters are usually square and hung on the back of the tank. They are easy to install and maintain, making them ideal for beginners and hobbyists. They have powerful pumps that move large volumes of water throughout the tank. Most power filters perform mechanical, chemical, and sometimes biological filtration.
Under-gravel filters Under-gravel filters perform only biological filtration. They consist of perforated plates placed under the gravel, which draw in water using a power had or air pump. They must be used with other filters to provide mechanical and chemical filtration.
Wet/dry filters Wet/dry filters sit under the tank and have large open chambers. They perform all three levels of filtration. The case is divided into sections for each type of filtration. They are commonly used in small reef aquariums. Good wet/dry filters are easy to install and require minimum maintenance. However, they are seldom sold with pre-fitted accessories. such as pumps. Some models can also accommodate heaters in the sump part.
Submersible filters Submersible filters are small and mounted inside the tank. They provide mostly mechanical filtration and must be removed from the tank regularly for cleaning. They may also be used in hospitals and fry tanks.
Diatom filters Diatom filters have filter bags coated with diatomaceous earth powder, which makes them very porous and absorbent. They perform advanced mechanical filtration that traps very fine particles down to micron sizes. They are not designed for regular use and and usually just “polish” the water after a regular filtration process.
| 
