Backyard Aquaponics
A place to discuss aquaponics

Hi Folks,

Was looking for some suggestions on the most energy efficient pump for taking water from a pond at the bottom of the garden to two greenhouses at the top of the garden for a GB system I want to install.

Distance is about 40ft with a rise of 25ft.
The filtered water from GB and filtration will return via a stream back to the pond.

Would also like suggestions on the positioning of the pump - external or in the pond.

Thanks.

Before you can go any further you need to calculate your total dynamic head.

Total dynamic head is your static head (elevation change) which in your case is 25' + the friction losses from your plumbing.

To calculate the friction losses we need to consider the flow you wish to achieve, as well as the pipe work you intend to use.

To give you an example, if you wanted to flow 10 UK Gallons/Minute and used 1" pvc pipe your head loss would be only 1.8' giving you a total dynamic head of 26.8'

If you wished to flow 20 UK Gallons/Minute using the same 1" pipe your head loss would be 21.3' giving you a total dynamic head of 46.3' which would require a much bigger pump.

Altering your design to reduce your total dynamic head will allow you to use a smaller pump, reducing energy consumption. You should also take into account any future upgrades, there's no point using a pipe that is good for 2 grow beds if you might consider having 3 or 6 later.

You can caluclate your friction losses using a calculator like this: http://www.calculatoredge.com/mech/pipe%20friction.htm

Once you have figured out your total dynamic head you can then start looking at pump curves for various pumps available to you locally.

You read these by looking at flow on one axis (you may need to convert your units, not all brands use the same units) and head/height (your calculated total dynamic head) on the other axis.

If no other information is give, a good rule of thumb is to use a pump where the duty you require it to perform falls in the middle 1/3 to 1/2 of the graph.

Good manufacturers however will give you a curve on the pump curve graph to show efficiency, you want to be at or very close to the peak of the efficiency curve (see below)


source: http://www.mcnallyinstitute.com/18-html/18-3.html

Then once you have found a bunch of contenders you can compare the electricity consumption.

If a pump manufacturer doesn't give you a curve, they may give you a table instead. If they don't give you anything skip that pump and find another.