First, lets determine how much water you have in your pond with your waterfall off – if you don’t know this, you can use this calculation:
Assume the pond averages are 8 feet by 4 feet and averages 2 feet deep.
Multiply average length (feet) x average width (feet) x average water depth (feet) x 7.48 gallons per cubic foot.
Example: 10′ x 6′ x 2′ x 7.48 gallons = 897 gallons (rounded)
You need to recirculate all the water in your pond at-least once every hour – meaning we should have a 1000 Gallon Per Hour Pump MINIMUM. You will likely want to have a larger pump for your waterfall and aesthetics.
Next, lets determine head pressure. The further the pump has to push water and the higher up will mean more head pressure requiring a larger pump.
10′ of PVC tubing = Add 1 Ft of Head Height.
1′ of Elevation Gain = Add 1 Ft of Head Height.
If your pump uses 20′ of tubing and has a 5′ elevation gain, you will have 7′ of head height.
Using the chart below, pick a pump where 7′ is in the green area (best operating zone for head height). These are Aquasurge pumps and work for almost all applications as they are submersible or external by taking the grill off and utilizing the provided fittings.
In this case, I may choose a AquaSurge 4000 to ensure i’m running the proper pump for the head height and ensuring i’m circulating the pond enough. Running the pump in the maximum operating zone will decrease it’s life and is not recommended.
If you like to have control over your flow, you can choose a variable pump at the bottom of the chart – in this case a 2000-4000 would be perfect. The pump can be turned up as desired and turned down when you are not around via controller at the pump or phone app. It is not recommended to turn your pump off with an Ecosystem Pond, especially if you have fish.