We are getting an 18x40 in ground vinyl salt water pool and live in Kansas. The deepest part of the pool is 6ft. We have read it’s better to get a heat pump as small as possible for the pool size to help with energy costs. But we want it to work well. What do you recommend? Top 3 choices? Also, what is the best water filter with good energy consumption? Lastly, we are worried about filling our pool with well water. What happens if pesticides are In the water?