ECONOMICAL HARD WATER TREATMENT: The Poly Guard Crystal System is an economical way to treat problem water. A reusable cartridge and four treatments are included for up to six months or 30,000 gallons each. Replace the cartridge in its entirety or just the crystals, as needed EXTENDED RELEASE CRYSTALS: The Poly Guard System slowly releases microscopic crystals into the water supply, protecting plumbing and water-using appliances from corrosion and hard water PROTECTS PIPES AND PLUMBING: The system defends against the ravages of hard water. Poly Guard extends the life of plumbing and appliances by forming a protective coating on metal and plastic surfaces preventing scale, corrosion and copper leaching PROTECTS PLUMBING AND EQUIPMENT: The Poly Guard System protects home and commercial plumbing systems, along with water heaters, water processing equipment and food processing equipment, from mineral buildup and eliminates rust stains in toilets, tubs and sinks CERTIFIED SAFE: The Poly Guard Crystal System uses food-grade crystals in slow release to protect the water supply in your home or commercial location. It is independently certified to NSF/ANSI 60 for drinking water, so that you know your water is clean and safe