what is the difference between a filter and a pump on a fish tank?

[Grant]

i'm getting a 20 gallon tank and i have a filter picked out but someone said i also need a pump. i can't find one on the petco website and i looked somewhere and they made it sounds like a filter and a pump were the same thing. it's going to be a saltwater tank for clownfish if that helps. please help, thanks!

[noob_2_net]

Sometimes the words are interchangeable but I believe what they are referring to is a power head which is a submersible pump used for better water circulation. A filter cleans and circulates the tank water. for a 20 gal tank I think a filter without the power head will be fine I would purchase a filter for a 40 gal tank better to have more filtration than not enough.

[fishobsessed!]

A filter is what establishes a biological filter in your tank (the build up of good, beneficial bacteria), and it also removes chemicals, toxins and other harmful things from your water. The tank water runs through the filter, where the filter just cleans the water and then returns it back into the tank. So the filter needs to be able to run fast enough so that if you have a larger tank, it is able to maintain keeping the water clean and livable for your fish to live. Your tank is very small so you won't need to worry about this. The pump is an 'air pump', its basically just a square box that vibrates and you connect a clear tubing to it leading into your tank which connects to either an ornament that will produce air bubbles, a bubble line/tube that runs along the wall of your tank that produces bubbles, or a air stone which is also produces fizzing bubbles. It provides extra air to the tank which is very important for some species of fish, if you fish is sick, if you have higher levels of ammonia in your water, and/or if you have lots of fish and less surface area of water for them to obtain oxygen from. Hope this helps!

As for the persons comment above mine.. this is what this forum is here for, so people can ask questions!