Interpet green away no4 100ml clears green water in aquariumsr excessive light or nutrients stimulate an unsightly and potentially dangerous algae bloom in aquariums which can effect oxygen and ph levels making the water quality alkaline and thus suitable for fishr interpet no4 green away clumps the particles together so that they become trapped in the filter or sink to the bottomr interpet no4 is for use in cold water and tropical freshwater systemsr one 100ml bottle of interpet green a