Pumping water up to the aquarium is hard work. Gravity and friction inside the pipe, tubing, and valves reduce the flow rate. The higher and farther the pump has to push the water, the harder it is for the pump to move the water which ultimately slows down the flow. This resistance is called “head pressure.” The higher the lift and longer the distance, the greater the resistance to flow.
If you ultimately need a flow rate of 100 GPH and selected a pump that produces a maximum flow rate of 100 GPH, you would be very disappointed after installing it on your tank. The tubing, elbows, and head pressure would dramatically reduce the actual flow rate. You need to choose a pump that is stronger and can deliver the flow you need AFTER the head pressure is applied.
In order to calculate head pressure, use the following standard formulas to add up the vertical rise, distance, and 90° turns to come up with a head pressure number.
- Every 1 ft of vertical rise = 1 ft of head pressure
- Every 90° elbow fitting = 1 ft of head pressure
- Every 45° elbow fitting = 0.5 ft of head pressure
- Every 10ft of flat horizontal distance = 1 ft of head pressure