To Drain & NOT Run or RUN & NOT Drain ??? !!!

[BritTim]

I have just found this forum & find it helpful. My question is about an in-ground pool in an area that has some frosts ( but not deep & long lasting. I am in the U.K. ) is it safe not to drain the pool therefore saving precious water & have the filter & pump switch on by means of a "Frost-Stat" placed in a timber poolhouse. If this is an acceptable method at what temperature would you suggest to set the frost -stat so that it switches on when needed but does not run 24 / 7 ? Also is it enough to prevent the pipes from freezing just by keeping the water flowing inside them? To drain a lot of water these days is not eco-friendly but to run anm electric motor too much is perhaps not good either.! Your thoughts & opinions would be much appreciated.
Thanks
BritTim