For green water issues, Rapid Clear, a flocculent that is 100% safe for fish, plants or wildlife, can be used. This product is a fast acting treatment that can solve cloudy water in just a few hours by physically causing the particulates floating in the water to clump together into larger particles that can be filtered out.
There are several other effective products that you can use to help clarify the water.  A combination of Beneficial Bacteria, EcoBlast and SAB Stream and Pond Cleaner is the ultimate way to have perfectly balanced, clear water. The Beneficial Bacteria and SAB both help consume excess nutrients in the water, break down decaying organics and reduce sludge and odor issues. SAB also includes a powerful phosphate binder that locks up this nuisance nutrient. These two products can be used as often as once a week.
Original post from Aquascape, Inc. dated September 13, 2015.