That is what the website said about it. Does nebody have one or has any insights about it. It looks neat but i wonder if it really works. Bypass filter for the elimination of phosphate The phosphate filter is a compact chemical filtration chamber for aquarium use. It can be installed in line with any standard canister filter, or via a separate pump. The phosphate filter contains 1 litre of antiphos. This reduces the level of phosphate and thereby curtails the growth of filamentous algae. Depending on the phosphate level, one filling of antiphos may be sufficient for an aquarium up to 100 gallons for between four and twelve weeks. The phosphate filter can be used for fresh and salt water aquaria.