TetraPond Pond Block, Helps Control Algae Growth in Ornamental Fish Ponds, 50 Count

CONTROLS ALGAE: TetraPond Pond Block Prevents algae growth in ornamental water fountains and ponds. DISSOLVING BLOCKS: For regular maintenance, replace blocks after they’ve dissolved, usually after 30 days. FOR CONTAINERIZED PONDS & FOUNTAINS: Not recommended for use with live plants. CLEARS CLOUDY WATER USAGE: Each block treats between 100 and 250 gallons of water.