Bests & Worsts Reviews from Amazon

The breakdown of barley straw in your pond water creates Hydrogen Peroxide which inhibits algae growth. You should not expect green water to clear overnight (but you already know this). H2O2 is only produced when the straw is rotting under well-oxygenated conditions and is near the surface of the water to properly mix with sunlight and dissolved oxygen, otherwise it sinks to the bottom and rots. Hydrogen peroxide in low concentrations such as this has no negative effects either on pond plants or on invertebrates and fish. Once barley straw has become active the time it takes to become effective varies with the type of algae. It will work faster on green water algae than mat or string algae, but still should take a month or so. I know you do not want to wait, but now you know how to keep it clear naturally and will love watching your fish. (As a disclaimer, this is what I researched and it has worked for me for 2 years.