Looking to install a natural gas heater on my pool. It's an inground vinyl I think about 15000 gallons. It will be salt water, pool gets full sun all day long. Just want it for when we have party's in case it is cold or rainy the week leading up to the party. Pool thermometer says im already at 80 degrees and I'd maybe wanna raise it to 86 during a party any advice on what size, I realize every one here speaks highly of Rheem so if like to stick to them if that is my best bet. Thanks in advance