HTH® Super Concentrated Clarifier. Restores crystal clear pool water. Does not affect pH balance. Improves filter efficiency. 1 balance. 2 sanitize. 3 shock. 4 prevent algae. HTH™. Helpline 866-HTH-POOL. Toll-free. Call 7 days a week with your questions concerning pool water care, 8:00 A.M. -10:00 P.M. Eastern time. Visit HTH pools www.hthpools.com. HTH® is a registered trademark of Arch Chemicals, Inc. The HTH™ logo is a trademark of Arch Chemicals, Inc. To determine pool capacity in U.S. gallons. Use the appropriate formula below. Pool shape: formula (use measurement in feet). Rectangular: length x width x average depth x 7.5 = total gallons. Round: diameter x diameter x average depth x 5.9 = total gallons. Oval: maximum length x maximum width x average depth x 5.9 = total gallons. Freeform: surface area (sq. feet) x average depth x 7.5 = total gallons.