I'm wondering if I have enough pump for my system. I couldn't find a calculator for this. My question is, when pushing water through storage tanks is there a significant amount of head added to the system total? I'm running 2) 250 gallon tanks horizontal in parallel. The inlets will be in one end of the tanks and the outlet will be in the opposite end. When the water pushes through the tanks what kind of numbers should be added to the total?