Removes unsightly algae fast from your aquarium! Algae Control™ not only combats aquarium algae, it also works to keep it from returning. Algae Control is highly effective against green water (algal blooms), blue-green algae, diatoms or "brown algae", hair algae or blanket weed that grow on the glass and decor. Unlike some other products on the market, Tetra Algae Control can be safely used in planted aquariums. Tetra's precision dropper tops help consumers administer the proper dose to their aquarium. One drop treats 1 gal.