Healthy Ponds 52500 Stock Tank Water Cleaner 250 - Reloadable Dispenser with 2 30-Day Refills; Treats up to 250 Gallons for 60 Days Contains a proprietary blend of naturally occurring bacteria that reduce the organic debris that collects in stock tanks Prevents stains, mineral deposits, odor and floating or suspended organic matter by consuming excess nutrients for improved water quality and clarity Veterinarian approved and safe for fish, plants, birds, animals and humans Because every stock tank is different, results may vary; some stock tanks will respond more quickly than others due to specific water conditions Includes reloadable dispenser with 2 30-day refills; treats tanks up to 250 gallons for 60 days