My neighbor's rain barrel went from 2 inches of scum to clear in one summer
I almost didn't notice it. He set up two barrels off his gutter in Omaha last spring, and by July one was green and smelled like a pond. The other stayed clear. Turned out he put a cheap diverter and a screen on the second one to keep leaves and roof grit out, and shaded it with a board. Cost him maybe $40 total. Anyone got a setup that holds up through a full summer without turning into soup?
Two inches of scum? That is nasty. I would have given up and dumped the whole thing out, so hearing it went clear in one summer is kind of wild to me. Forty bucks seems too cheap for a fix like that, but a screen and some shade makes sense when you think about it. My barrel goes green every single August no matter what I do, so I might try the board trick first and see if that alone helps.