Generally, how do filters work in an aquarium?

Generally, how do filters work in an aquarium?

Marc Grover (Professional Aquarist) gives expert video advice on: Generally, how do filters work in an aquarium?; What are the best filters for a small freshwater aquarium?; What are the best filters for a large aquarium? and more...

When you're talking about filtration in an aquarium there are three basic types in any type of system. There's biological, chemical, and mechanical. Biological literally grow and house aerobic oxygen-using bacteria which convert, by basically eating ammonia and nitrite, and the by-product or the waste product ends up being nitrate which is not very toxic. That's your basic biological system. It is aerobic bacteria needs good rich oxygenated water to go through, either your gravel bed or your wet-dry triple filter where they live. Chemical filtration is typically either a hang-on filter, that hangs-on at the back of the tank. A section in the wet-dry that houses carbon or some kind of mechanical absorption resin that specifically targets uric acids, copper, other heavy metals that while not deadly to a fish but most of the time can cause some concerns or some issues for them. And the last thing is really what I call the people filter. It's the physical-mechanical part of the filtration system. You're using a type of padding, or a type of floss or cotton to physically pull out particulates, whether its pieces of plant or excess food, anything in the water that will be a particle you could actually see with your naked eye. Those particles will tend to make the water look not as clear as it should. And if you got a good mechanical filter, it'll literary extract those components out and make your tank crystal clear.