Hello. My first time asking a question of this forum. I am planning on adding a NG pool heater to our existing, six month old pool for next winter. What might be the best &/or optional gas pool heater. Our pool is approx. 15,000 IG, facing S. It is a salt pool which uses a Pentair IC 40 salt cell, a Pentair VS 3050 pump with a Pentair clean & clear 420 Cart filter. The pool perimeter is 99 ln. ft. with a surface area of 467 sq. ft. It has an in floor Q-360 cleaning system. The pool slopes from 3.5 ft. to a max of 5 ft and has one shear water feature. Our current readings have been steady at 3; 7.4; 80. We have a natural gas line installed next to the pool equipment which could support 400K BTUs. Not certain if I need a 400K unit ie Pentair vs Hayward or could get by with a smaller 250K unit. Also, as it is a salt system, do I need a heat exchanger that is less effected by corrosion such as a Cupro? Any and all responses welcomed. Thanks.