I'm building a solar hot water system to help heat our hot tub. I'm curious about what kinds of piping material would be appropriate from the collector to the tub. The collector itself is made with copper tubing, and the control center (pump, expansion tank, pressure regulator, etc) is all plumbed with 3/4" copper pipe. However, it would be handy to have something cheaper and flexible to go from this to the tub itself, and once in the tub cabinet, to loop around to the heat exchanger. Would Pex be a suitable material?