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Not to mention that 60 degree water would be FREEZING anytime of year. 85 degree water feels cool. Wouldn't take long to cool your tub to 85 and then back again.
Hot Spring and Caldera are both owned by Watkins Wellness and are the only spas that can use coolzone. I sell both brands and have never seen or sold coolzone, and probably never will. The $1600 price you are being quoted is a good price, but unless you absolutely need to be able to cool your hot tub, I don't see the value. I would either put the money towards ACE or save it.