Work good. Cause that was al ays issue . We had some dam little bitty fish that ate the algea and such. It's was the only way to defeat that at the time.Scum/algae in the buckets is bad, and is usually related to light leaks. I'd hose out any scum when changing the buckets. I also use beneficial bacteria (Hydroguard / z7) to try to keep the scum to a minimum.