only disadvantage is that it can be a little expensive if you need to fill up a big canister filter.
Marineland Biofilter Balls
Marineland Biofilter balls are the traditional non-porous balls of plastic designed specifically for eliminating ammonia and nitrite only. There are no pores present to trap debris and provide support to denitrifying bacteria, so water flows easily through and over them. These biofilter balls are ideal for freshwater, planted fish tanks and fish-only saltwater aquariums having canister filters. It does not require any replacement and never gets dirty. It is an effective, inexpensive bio media with the only disadvantage of not have nitrate removing ability.
Aquapapa 6lb Premier Bio Ceramic Rings
The Aquapapa Bio Ceramic Rings are packaged in a mesh bag that is fish safe. They are designed to be used in both freshwater and saltwater aquariums. They are non-floating rings that are almost 0.5 by 0.5 inches and are applicable in most of the filters, reducing ammonia, nitrate and nitrite levels effectively. One of its main features is the increased flow rate and the following oxidation. They are easy to maintain as well. Their only downfall is that bacterial colonies take a small time to establish themselves.
Aquarium Equip’s Filter Bio-Sponge
Aquarium Equip’s Filter Bio-Sponge is basically a pad of foam that can be used in sumps, wet or dry filters, and canister filters for all aquariums. It is structured from a dye-free plastic substance. Its large porous surface is perfect for bacterial growth. It prevents clogs but needs cleaning in 10-20 days. However, it can be used many times. This bio-sponge can replace filter block and reduces nitrite, nitrate, and ammonia levels efficiently. You just might need to cut it according to the size of your filter.