Aquadyne Model 2.2BHE (High Efficiency) Bead Filter Perfectly suited for koi ponds up to 7500 gallons. Diameter 24, height 42, maximum pressure 50 psi. - Plumbing is 2 on all ports. Average water to backwash 50 gallons. Average flow through filter 1000-4000 gph. Minimum flow for backwash 2500 gph.