I am replacing a broken heat pump. I am getting a propane heater because the heat pump took too long to heat the pool. For a 20,000 gallon 18x38 concrete inground pool, what brand and/or size heater would you recommend? Can you tell me how many degrees per hour heaters at various btus would raise the temperature? I think I need 300 to 400 thousand btus, but any advice would be appreciated. I want to be able to heat the pool quickly. Also, any advice on features I should have would be appreciated.
Thanks.