4-pack of refills for Healthy Ponds® floating lily or submersible dispensers. Each refill treats up to 1,200 gallons (to calculate pond volume in gallons, multiply length x width x average depth x 7.5). Being all-natural, you can"t overtreat. PRO formula works effectively in water from 34° to 110°F. Safe for humans, pets, fish and plants. May require 4-6 weeks to achieve water quality improvement. Most effective in ponds with pH level between 6.0 and 8.5. Four packets provide 120 days of treatment. Made in USA.