Some friends have a German system made by Lorentz. It is driven by a DC brushless motor that is apparently extremely efficient and reliable. They have it connected to the solar generator through a controller that monitors monitors the system, controls pump speed and volume and temperature of the water circulaing based on power available. They have clear light, that is to say no house or trees shadows, that obscure their PV panels thus restrict power generation, and can bathe all year round. Both are sports teachers so feel that is a justifiable essential. The downside is that it is quite expensive, their pool being a bit bigger than your 10m x 5m may have some bearing on installation needs and price of course, however they are also entirely power independent using ground sources, PV, conventional solar water heating and wood so have the entire set up in place. They are neither affected by power cuts nor have mounting bills is one of their main arguments, certainly the pool is constantly available.