Pool unit treats 7.5k-20k gallons pools, effective for up to 6 months. Simplifies pool maintenance, suitable for all types of swimming pools. Maintaining pH balance is crucial to ensure the effectiveness of chlorine. Under normal circumstances, as long as the instructions are strictly followed, you can actually see and feel the difference in the quality of water within 24 to 72 hours. Easy to use: 1. Remove debris from the filter/pump basket. 2. Place this device into the filter/pump basket. 3. Run the pump for 6-8 hours. Pool unit treats 7.5K-20K gallons,Up to 6 months,Simplifies pool maintenance,Compatible with all types of pools