Bio Start contains biological cultures which rapidly establish the essential biological cycles required to remove fish waste ensuring that the water in your pond is safe for fish. This sachet contains 8,500 million bacteria to consume the fish waste. Fish disease and death results from poor pond water quality, which can be caused by fish waste building up to toxic levels.This dangerous condition typically occurs in new ponds and in spring. Each sachet treats 500 gallons of pond water (2273L) This listing is for one sachet Suitable for all new pond startup\'s and after water changes and media replacement.