TetraPond Sludge Reducer adds beneficial, enzyme producing bacteria to the pond bottom, degrading organic debris and reducing sludge buildup. It helps keep water clear by reducing debris. By minimizing sludge, water clarity is improved as turbulence caused by swimming fish can agitate sludge and cloud water. Sludge Reducer is particularly useful in ponds with stones at the bottom where netting and vacuuming debris is impractical. For use in ponds with fish and plants. Great to use in spring before water is shaded by aquatic plant cover. Use regularly in spring and summer. 16 oz treats 16,000 gallons of pond water.