4 Easy Steps to the Perfect Pump
- Determine the desired visual effect of your waterfall
- Size your tubing to maximize water flow
- Find the Total Dynamic Head of the feature
- Select the perfect pump…….or pumps!
1.) How to know how much flow?
First, Determine the total width of spillway(s), then choose the appearance desired.
- Trickle- 1/4″-1/2″ depth of water over spillway = 50 gallons/hour for each inch of width of spillway.
- Sheet- 1/2″-3/4″ depth of water over spillway = 100 gallons/hour for each inch of width of spillway.
- Niagara- 1″-1 1/4″ depth of water over spillway = 200 gallons/hour for each inch of width of spillway.
Example: 16″ wide spillway at a medium flow; 16″ x 100 = 1,600gph
30″ wide spillway at a high flow; 30″ x 200 = 6,000gph
2.) Pipe & Hose Sizing Chart
For maximum efficiency and longevity of the pump and plumbing
Tubing Size I.D. Flows up to (GPH)
1 1/4″ 1,350
1 1/2″ 1,950
3.) Calculate the Total Dynamic Head of your Feature
Calculating the precise Dynamic Head involves some math and the ability to use friction loss charts. It’s not really that difficult, but for our purposes here, we’re going to really simplify things to the most basic level.
The formula for calculating Total Dynamic Head is:
Static Head + [(horizontal distance+fittings)/100 x Friction Loss]
(static head = the vertical distance in feet from the surface of the body of water to the maximum level water is being lifted)
You’ll need to refer to friction loss charts to get the total loss through fittings and input them into the above formula.
For now, let’s just use some “rules of thumb” shall we?
- Add 1 foot of head for each 25′ horizontal feed of tubing
- Add 1 foot of head for every check valve
- Add 1/2 foot of head for every other fitting
Add this number to the static head, and round up to get the Total Dynamic Head.
So lets say your waterfall is 4′ tall, with a 30″ spillway, your pump is at the far end of the pond 25′ away, and the visual effect you desire is Niagara Falls.
- Static Head = 4′
- 25′ Horizontal tubing = 1′ Head
- 30″ wide spillway x 200gph = 6,000gph
4.) Select the Perfect Pump
Assuming you have no check valves, ball valves or other fittings and your tubing connects directly from your pump to your waterfall, you would need a pump that would deliver at least 6,000 gph at 5′ of lift. Refer to the flow curves on the pumps to determine which pump meets the criteria.
Choose the type of pump that provides the desired flow in GPH through the optimal tubing size at the correct Total Dynamic Head for the least wattage consumed.
What Types of Pumps are there?
- MagDrive – Low to Medium Head – up to 12′ TDH, 0-5 psi
- Pro – Very Efficient, Dependable, Simple, Replaceable Impeller
- Con – Bidirectional, inefficient impeller, magnet size, noise
- Asynchrounous (Hy-Drive) – Medium Head – up to 20′ TDH, 0-8psi
- Pro – Very Efficient, Dependable, Quiet
- Con – Non-Replaceable impeller, flows drop off at high head
- Direct Drive – Medium to High Head – up to 50′ TDH+, 15 psi+
- Pro – Solids Handling, Efficient Impeller, Great Head/Pressure
- Con – Seals, High Power Consumption, Heavy
Special Thanks to Demi “The Pondman” Fortuna for contributing his other worldly expertise for this article.