Pond and Aquarium Algaecides
Algaecides, or algicides, are the fastest way to destroy algae and cyanobacteria (red slime/green slime) in your aquarium or pond. They are not a long term solution to pervasive algae problems. Some algae is unavoidable - control it with regular cleaning & partial water changes, good circulation, diatom filters and protein skimming. Algaecides create a large load of waste (dead algae), so regular filter cleaning and partial water changes until conditions stabilize will prevent further problems.
Algae problems may be caused by phosphates or silicates; remove them with chemical filter media. Direct sunlight causes blooms, as do lights not meant for aquariums. Unless specified otherwise, avoid algicides in planted tanks, reefs, or tanks with livebearers or crustaceans.