Water clarifiers

Water clarifying agents are flocatting (clumping) agents that basicly react with the oxygen in your water binding anything in its path together. They won't harm your fish if you only use it once in a blue moon. Just make sure you follow the dosing instructions to the letter and increase airation while you use it since it does take oxygen out of the water. Cleaning your filter after it has done its job is reccomended since the polymer does break down eventually. It won't harm the biofilter either.