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 fishr this sachet contains 8 500 million bacteria to consume the fish waster fish disease and death results from poor pond water quality which can be caused by fish waste building up to toxic levelsthis dangerous condition typically occurs in new ponds and in springr each sachet treats 500 gallons of pond water 2273l