Keep your pond water fresh and clean with API Pond-Zyme Sludge Destroyer Pond Sludge Remover. Made from specially selected bacterial strains, this additive breaks down fish waste and dead algae that cause cloudy water, sludge build-up and debris that clogs pumps and filters. This all-natural product is safe for all pond fish, plants and wildlife, and reduces pond maintenance making it easier to take care of your aquatic friends. Just dose once at the beginning of the spring season and once for maintenance every two weeks to keep your pond and your fish happy and healthy.