Tetra Algae Control liquid combats auarium algae and works to prevent it's return. Tetra Algae Control liquid not only combats aquarium algae it also works to keep it from returning. Algae Control liquid is highly effective against green water (algal blooms) blue-green algae diatoms or inbrown algaein hair algae or blanketweed that grow on the glass and decor. Unlike some other products on the market Tetra Algae Control liquid can be safely used in planted aquariums. Tetra's precision dropper tops help consumers administer the proper dose to their aquarium.