Ideal for Pool Opening & Closing: Natural Chemistry's Pool Magic Spring and Fall + PhosFree gives pool owners with a treatment designed to make opening and closing their pool much simpler and easier, along with adding PhosFree to eliminate any phosphates in your water. Eliminates Water Rings: Utilizing natural enzymes that stabilize pool water through the winter, it eliminates much of the prep work commonly involved during pool opening, and virtually eliminates the formation of water rings, stains, while protecting pool liners and finishes. Quickly Eliminates Phosphates: Pool Magic + PHOSfree is perfect to use after a heavy storm to quickly eliminate phosphates that were introduced into the water. Works with Mesh Covers: Pool Magic + PHOSfree works well with mesh covers, providing optimal performance and enhancing the effectiveness of your pool maintenance routine. Tested and Proven Effective: Natural Chemistry products are known for delivering reliable results and making water care less complex. Natural Chemistry carries an extensive line of pool and spa solutions that match your unique needs. Details: This Natural Chemistry pool magic phosfree is ideal to treat your pool at the beginning and end of each season and to eliminate phosphates at any time. No phosphate build up. Provides fast easy start-up. Maintains low phosphates all season. Prevents waterline rings. Helps preserve pool liners and finishes. Great for end of pool season. Open clean, clear pool following off-season. Makes water feel soft and silky. Recommended dose is 1 liter treats up to 20,00-gallons of water. Removes up to 300 ppb (parts per billion) of phosphates from a 20,000-gallon pool. For closing pool application instruction are shake well before using as contents settle. One to two weeks before closing, add required amount of product directly to skimmer. Close pool normally after adding product. Includes 12 pool magic phosfree container per pack. Comes in 1-liter container.