Hi Albie, I notice that you suggested a low pressure pump. Surely you will have to use a pump with at least a 5 meter head(high pressure)
I have seen that it works very well on swimming pools to heat up the water. My only concern is the bad bacteria that will grow in the pipes when you bypass the system. Standing water in a pipe at high temperature is a fantastic breading ground for nasty bacteria. As soon as you open the system after a bypass, all that bacteria will flow into the pond?
One of my clients who had the same problem, created a shallow veggie filter with large surface area in direct sunlight in a different spot in the garden. This effectively raised his pond temperature with a few degrees, effectively increased his overall volume of the sytem to allow larger stocking densities in his pond and increased biofiltration.
The problem is that not everybody has the space.
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