Tetra Algae Control

I picked up a small bottle of this to see if it would do anything for green algae growing on the substrate and green water. I tested it in two tanks, one with some green algae and one with diatom algae. It did nothing to the diatom algae or the green algae that was on the substrate of the other tank, from what I could see. I added a dose every 2 days (1 day earlier than they direct you to do). It did seem to clear up free floating algae in the one tank caused by too much light. If anyone is having trouble with green water I'd give this a try, it's only a few bucks for a small bottle. I wouldn't recommend it for any algae actually growing on surfaces since it did not seem to have any effect on it.