Posted by Scott Willbanks to Pond Pumps
To figure out what size pond pump you will need to run your pond efficiently you must determine your head height.

First decide on what kind of flow you will want based on your size pond and waterfall width. For most ponds over 1000 gallons and under 5000 you will want to turn your water over at least once an hour. Ponds that are over 5000 gallons can be turned over every couple of hours. And smaller ponds under 1000 can be turned over more than once an hour. This can vary depending on the pond however this is a good general guideline to follow.

If you have a waterfall how wide is it? For every inch of width of waterfall you will want 100 gph for a nice flow of water. Wanting Niagara you will want more water per inch. This is a general guideline and a smaller water flow still can look nice over the waterfall. It’s all about what your desire is.

Example: For a 3’ wide waterfall you would want 3600 gph giving you almost 3/4” in thickness of water.

Figuring out your Head Height:

Static Head:
Measure from the ponds surface (not the bottom of the pond) straight up vertically then looking over to the highest discharge point, usually the top of your waterfall.  This is your static head.

Friction Head:

Know your size diameter of hose. Measure the total amount of piping or tubing from your pump to the end of where the water will discharge from. Then count all fittings especially 90 degree elbows as these will add to your friction. Refer to the Friction Loss Chart to determine how much length of pipe each fitting is equivalent too. Figure out the total between length of pipe and adding your fittings for your total friction head.

Example: My desired flow is 3600 gph. I have 30’ of 2” pipe with four elbows. According to the friction loss chart my fittings will be equivalent to an additional 25’ of piping. Total piping would then be 55’. At 55’ with 2” pipe using the calculations on the chart for 3600 gph this would give 3.2’ of friction head. If we had used only 1 ½” pipe our friction head would be 10.9’.

Special Note:  Diameter of Hose can make a huge difference in water flow. The larger diameter the hose the easier it is for the water to go through, creating less friction and less head height.

Pressure Head:

This is the resistance that you get from a pressurized filter and or a UV light. Most small pressurized filters will add around 3’ to 4’ of head. Filters such as the Ultima filter will add 10’ of head. Bead and Sand Filters even have a greater head height.  Remember that as a pressurized filter becomes dirty the resistance increases and in return the head increases. A Pond UV light will usually add around  1 to 2’ of head depending on the shape.

Add your Static Head + Friction Head + Pressure Head to get your Total Dynamic Head. Then look at a pump taking your Total Dynamic Head at the flow you desired to see if it will work for your application.