4-pack of refills for Healthy Ponds® Fountain Water Cleaner. Each refill treats up to 25 gallons. 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. Four packets provide 120 days of treatment. Made in USA.