PoolRx Blue Mineral Chemical Removes Algae For Swimming Pools - (Various Size) PoolRx™ helps eliminate algae and reduce the amount of chemicals used to sanitize the pool. Place it in your skimmer or pump basket, and it instantly becomes effective. The specially treated alloy cylinder is packed with a proprietary blend of minerals that rejuvenate every time they pass back through the cylinder. The cylinder last up to 6 months, at which time you may need to add a booster pack according to the gallons of pool water. PoolRx™ is also ideal for salt water pools by reducing the salt chlorine production needed to keep your salt pool algae free. Less salt chlorine production extends the life of the salt cell and reduces the amount of acid needed to balance the pH. Directions For Use Clean or backwash pool filter Place the unit into pump basket or skimmer ideally in pump for increased water flow Initial run time at least 3-4 hours to ensure minerals completely dissolve Pump should run during the heat of the day at least 6-8 hours Do not re-clean or backwash filter for at least 2 weeks