I purchased a house 4 years ago with a ~12000 gallon in ground pool. In that time we have replaced a motor on our Hayward induction (?) pump (1hp) and put in a sand filter. We=the pool guys who take care of our pool. We are having installed a solar heating system on our two story house. Although two story, the house has some one story roofing and the overall system is probably averaging 1.5 stories. My pool guys say the pump and the sand filter can't handle this due to back pressure from the solar system being so high up. The solar people says it will be no problem, althought recommend replacing the pump with a variable speed pump (Pentair-intelliflo). My pool guys say that if I insist upon doing this that I should insist on 3" lines going up to the roof. I am doing my best to become educated in the matter in order to make the best decision. Any advice/information you could provide would be greatly appreciated.