I have this filter along with a Fluval 205 on a 55 gallon goldfish tank. The little Fluval is doing all the work. This canister filter is only equiped for mechanical and chemical filtration when, as we all know biological is by far the most important. There is no room for bio filter media. There is a seperate bio-wheel attatchment for bio filtration. I do not use carbon and so filled the carbon chamber with ceramic rings for bio media. There is VERY little room to add the media of your choice. This filter does a good job at mechanical filtration and my water is generally clear. For only a bit more money you can get an AquaTop or Fluval- both much better in my opinion with a lot of room for media. On the upside the customer service is great- I've called multiple times because of problems and they always help. The filter is simple to assemble and maintain.