I have read up a bit on this pump and I am a bit skeptic on their statements. I know they won't say things that is not true but to refer to a pond's turnover rate as once in 6 hrs using a pump that delivers 12000 lt, that is a large pond and then they claim a reduction of power from 750 down to 280 W for a loss of only 3400 Lt.
down to 9100.
When I make my sums I come up with interesting things:
1. You start off using ,06Watt per 1000 Lt
2. You end up using ,03 Watt per 1000 Lt
3. Then your saving equates to .08 Watt per 1000 Lt (sounds high to me) You cannot save more than what your original usage are
(all figures rounded and are roughly used to demonstrate the principals)
A standard , 75 Kw gives you around ,045watts per 1000 Lt
Well then I think one will be better of using two pumps. 1 that pumps 12500 and one that can pump 9100 using a timer on both to operate individually. as and when needed.
The delivery rates mentioned is all typical of the pumps set up in ideal situations and no friction are taken into account here, I am sure. So the delivery rate for the quoted pump at 750W should not be relied upon. That wont be the volume of water that goes into your pond.
I personally think that we have to be patient for a little longer better low wattage pumps will shortly be available.
So in answer to your question, I don't think it is viable.
The Americans have been using two speed pumps at what seems low wattages but there voltages are only 110 and when you make the sums there is no saving there either.
I think the important thing here and it was with the thread that went wrong is: How much does it cost us per 1000 lt for the water we actually get into our ponds and why?