Pentair Pentek Big Blue Heavy Duty Filter Housings offer the versatility to meet all of your large-capacity filtration needs, including highflow and heavy-sediment applications. The extra large housing allows for greater cartridge capacity, reducing the number of vessels required for high flow-rate applications. Sumps are available in both 10" and 20" lengths. The High-Flow Polypropylene (HFPP) cap is available with 3/4", 1" or 1-1/2" NPT inlet and outlet ports. The 1-1/2" internal port allows a greater volume of liquid to pass through the HFPP cap more rapidly. Big Blue Housings are compatible with a broad range of chemicals and are available with or without a pressure relief button. They accept a wide variety of 4-1/2" diameter cartridges.