Anyone who runs a pond year round needs to make sure they get a head start on their algae control. One of the best ways to do this is to use either barley straw pellets or barley extract!
Barley pellets are placed in a bag and set into the pond where they are getting good flow; skimmer boxes or waterfalls are good place to put them. In cooler water (50F and below) they will take 6-8 weeks to start working. In warmer water (68F and above) they will take 1-2 weeks. The pellets should be replaced every 3 months.
Barley straw extract is used every week for the first 4 weeks then once a month as maintenance.
As barley breaks down it releases enzymes that break down organic waste in the pond and out competes the algae growth in the pond.