GLB filter cleanse is perfect for cleaning your swimming pools filter in early spring to remove any winter debris as well as using for closing the pool in the winter. This cleanser changes from red to yellow as it cleans so you know when the cleansing period is done. This product is compatible with , bromine, salt water, ozone, minerals and biguanide filters. Product Features:. Swimming pool and spa filter cleanse Compatible with , bromine, salt water, ozone, minerals and biguanide pools. Changes from red to yellow as it cleans. Unclogs and cleans filters from grease, oil and scale. 2lbs - 1lb per treatment