I have been slowly winning the battle with green water, but finally caved and got a cheap UV sterilizer (the green machine ) and I can't believe the difference. Way more clear than even before I had the green water problem. I can't believe that they aren't considered necessary equipment. I have 10 or so Cherry Shrimp, and haven't had any problems as of yet. They eat the surface algae, and the snails eat the algae growning on the glass. I also feed the shrimp algae wafers when I feed my sae.
Hope this helps, I wish I had gotten one years ago.