I have a question for anyone who's had experience with the Hot Springs 'Cool Zone' feature. I'm considering adding this to my spa (an Envoy with the Ace system) in order to be able to use it year-round. I'm in the "mountains" of north Georgia, and I get the sense that the water temp wouldn't be quite cool enough to be 'refreshing' on a hot day without this addition. However, I'm open to hearing what others think about this. If you have the 'Cool Zone', what do you think of it? If you didn't add it, do you find that the water stays sufficiently cool just by keeping the cover closed until you want to use it? (I notice that the cover is a surprisingly good insulator. I expected to lose WAY more heat overnight during the winter months.) Any advice here appreciated. First time spa owner. Loving it so far.