Step 5. Filter Sizing Bad install Choose the proper filter based on the design flow rate and turnover rate. See flow rate chart. Figure 1 FLOW RATE Filter Type Commercial Residential DE 1.5 gpm 2 gpm Cartridge .375 gpm 1 gpm Sand 15 gpm 20 gpm Gallons per minute to sq. ft. of filter media surface area. Air Lock Bad install Figure 2 90 degree elbow too close Proper Pump Installation • P  ump with air lock is bad installation (see Figure 1). • Pump with 90° elbow is bad installation (see Figure 2). • G  ood installation should not have an air lock and should have 4x the pipe diameter going into the suction side port (see Figure 3). • B  est installation uses Sweep Elbows for maximum efficiency (see Figure 4). Good install Figure 3 4x pipe diameter into pump Best Install Figure 4 Sweep Elbows in/out for maximum efficiency 2016 Zodiac Pool Systems, Inc. Product Catalog 29