This clarifier is designed to do two things. It will tie up excess phosphorous in the water column which is a necessary nutrient for algae production and it helps tie up suspended soil particles giving you a clearer pond. This product is an alum or aluminum sulfate based product that is commonly used by water treatment plants to tie up excess nutrients and as a flocculent to remove suspended dirt particles and to reduce turbidity.
Product can be used year around. Most people apply one to three times per year. Each 10 lb. container is designed to treat up to 1/4 acre. For a 1/2 acre pond, you would use 20 lbs.