Filamentous algae are still there. Even if a few die of ugly gray / green mucus remains. You have so nice looks clean each infested stone it again. The composition itself is only conditionally, started with the recommended amount and when it did not work then slowly increased but really do not want to act. Unfortunately, there seems to be no remedy which will really help against string algae. The price is also not without, so I little effect and the high consumption only two stars awarded for.