You'll love everything about BioGuard's Mineral Springs system. For starters, it's almost "hands-off," and takes only a few minutes a week to maintain. In fact, once you've begun the system, you only have to add the Renewal® product once a week. The Mineral Springs system is perfect for frequent travelers or vacation-takers. Through proper use of the system, you can leave home and forget your pool while you enjoy your trip. Even better, with Renewal you can add advanced applications for weeks ahead. Replenishes lost mineral levels and rejuvenates the Mineral Springs® system. Renewal® contains pH balancers and adjusters to offset pH drift including chelants and scale inhibitors. This helps prolong the life span of the Mineral Springs electrolytic cell. Renewal also contains a filter aid and helps in maintaining crystal clear water. Apply one bag per 20,000 gallons weekly to replenish mineral levels. Available in a 4 lb. bag. Our Resident Chemical Expert says: Through normal pool use we lose water through splash out, evaporation, back washing and dilution from rain. You add 1 lb. per 5,000 gallons of water. What this does is bring up all the levels of salts, help balance PH , introduces a filter aid to keep your water sparkling and a scale inhibitor to help prolong the life of the salt cell.