At the bottom of most ponds, there will be a built up of sludge. Sludge is caused by decomposing plant, animal & fish waste matter. Over time the sludge can harbour harmful bacteria & micro-organisms that cause disease & infection & can turn your pond water cloudy & unsightly. By using Bermuda Banish Pond sludge, you can safely & effectively removes the sludge without upsetting the ponds natural balance. 250ml will treat ponds up to 5682 litres/ 1250 gallons in size.