Healthy Ponds Bird Bath Water Cleaner treat bird baths up to 7 gallons. Delivered in disposable, floating plastic dispensers; each dispenser is effective for up to 30 days. This product is efficient in the prevention of stains, mineral deposits and organic build-up found in bird baths. A natural approach, it is safe for all surrounding animal and plant life. Veterinarian approved and safe for all birds and wildlife. Dispensers should be replaced every 30 days for continuous optimal results.