Hydromatic Model SKHD150 High-Head Effluent Pump 1-1/2 HP Cast Iron, 2" NPT Discharge, 3/4" Solids Handling - Generates high heads for bigger drain fields. The Hydromatic SKHD150 submersible pump is specifically designed to meet the demands of septic tank effluent and industrial sump applications that require a “high-head,” dual-sealed pump. The 1-1/2 inch NPT discharge pump is available with a powerful 1-1/2 horsepower motor, which provides maximum starting torque.