Having an issue with greenwater in an outdoor pond, last week it was crystal, yesterday, it was opaque. I don't actually know exactly how big the pond is, but I'd estimate it as maybe 6'x10' and 4 to 5 feet deep. It's not mine, but my grandfather's, except he's really been touch and go the past year, and hasn't been able to attend to the fish lately. Any information on how to handle greenwater on this scale would be greatly appreciated. I'll probably be going up to my grandparents' later this week to help my aunties figure this out. My grandfather really is the only fishkeeping-literate person at the house at the moment, but he's not been up to talking so much.