API® 146B Pond-Zyme® Sludge Destroyer Pond Cleaner with Barley, 16 OzPOND ZYME is a super concentrated blend of dry bacteria and natural barley that keeps pond water clean and clear. Organic matter accumulates in all garden ponds, forming unsightly sludge. As the sludge decomposes, it consumes oxygen, degrades water quality, and clogs pumps and filters. It is also a breeding ground for fish pathogens. The specially selected bacterial strains in POND ZYME work quickly to remove sludge build up. Size: 16 Oz (454 g)