For residential inground or aboveground swimming pools requiring turnover through 59,000 gallons. Permanent media high rate sand filters in multiple diameter models accommodate large and small pools, offering the best combination of economy, performance, durability and ease of maintenance. Corrosion resistant, one-piece, extra-thick molded polyethylene tank assures long service life. Top-mounted, corrosion-resistant multiport selector valve included. Also includes a convenient tank winterizing drain and continuous air relief system.