Keep your pond fresh and clear with the cleansing power of beneficial bacteria and enzymes. Regardless of how large your pond is (up to 225,000 gallons), the Aquasphere will clean it for a full 30 days. Easy to use, reducing excess nutrients and breaking down organic matter that clouds water. Choice of two sizes: 50,000 gallons and 225,000 gallons Non-toxic and safe for fish, pets and aquatic plants Use when water temperature is 50 degrees or warmer Note: If you are ordering this item as a gift and it is the only item on your order, please be aware that there is a picture of the item on the outside of the delivery box Measures 6" diameter Recyclable, not refillable Not for control of duckweed To calculate pond gallons: Length (in feet) x width x average depth x 7.5 = gallons.