EasyPro SRB24 Pond Sludge Remover Bacteria, Dry, 24 Packets Recommended for ponds with gravel covered bottom where sludge can build up 1-ounce water soluble packets for easy application Removes sludge and odors, extends filter life between cleanings Dosage: one packet per 1,000 gallons of pond water Apply weekly in spring/summer as needed