API Algaefix Marine 473mlAPI Algae Fix Marine is a reef safe aquarium algaecide. Controls many types of algae in marine and reef aquariums. Will not harm marine fish, corals and other invertebrates. Will not harm coralline algae. Effectively controls Green algae, Red Slime, and Brown algae in marine aquariums containing live corals, invertebrates and fish. Use weekly to control algal growth and reduce aquarium maintenance. Does not discolor water or cause foaming.