I have a 24' round AGP. I estimate that a 100k btu gas heater will work fine actually down to a 65k. I live in North Eastern Ohio and look to extend the pool season a bit. I like my pool on the cooler side 77 - 80 degrees works for me. What should I expect cost wise operationally? I know there are a lot of factors and I think it would be more of an intermittent usage rather than a constant temp. trying to weigh things out a bit for next year.