New from Helix Life Support, Rock & Waterfall Scrubber works quickly and safely to remove debris from rocks, waterfalls, streams and anywhere build-up has occurred in your pond. This product is fish-safe, relying on the natural cleaning power of oxygen to rid your pond of unsightly build-up. It also restores a natural electrolyte balance to your pond with a slight buffering effect to help prevent dangerous pH swings. The 32 oz container has enough to treat up to 320 square feet.