We have a pool at home with 70m3 water. We live in Spain, where it is warm may to october but we want to heat through the winter (using a cover). We have been recommended 2 brands of heat pumps. A Fairland Inverter plus. Or a Hayward? Can you give me any further information on what to look for in a pump. What size and spec you think we need. It's all new to me! Thank you, Sarah