I want to buy a heavy-duty heater and like I said, I don't mind spending a little more money if I get something that is really good quality. But what I don't want is to pay big bucks for something that I get home and then find out can't be installed on my AG pool. But everything that I see for AG is about 100,000 btu. And according to my calculations I would want at 150,000 btu minimum.... all of which are called "in-ground pool heaters." I will have to talk to someone that sells them at the pool store I guess, but that is always a last resort because I get such bad information from them so often. That's why I posted the question here first to see if someone might know the answer.