I'm a spa newbie myself, and only slightly more experienced in pool care. We put up our pool last summer and then this summer we added the hottub. When the tub was delivered in July, the installers saw our pool with its beautiful, glistening, crystal clear BBB water and decided to pump pool water over to the hot tub to fill it rather than use the tap water. While it seemed like a good idea at the time, I now have some doubts. The first month the tub was up and running with that pool water in it, I just couldn't seem to get the hang of maintaining proper water balance and sanitizer levels in the hot tub. Levels kept fluctuating on me and I couldn't seem to predict how the tub was going to behave. I also noticed the jets and venturis started gumming up and sticking. Many of them I couldn't operate at all anymore. I was starting to think that maintaining a spa was beyond me! It never occured to me though that the problem may have been in the water I started with. At the end of August I decided to do a complete water change, mostly because I wanted to do it for the first time while the weather was nice outside, plus I was a little bored one day to boot. So I drained the tub and refilled it, this time using tap water. I balanced the pH, and TA and put my bromine starter and floater in. Since that water change, I have had none of the chemistry problems I had noticed the first time around! The pH has been much more stable, the sanitizer level has been much easier to keep up, and the gummy jets and venturis have been functioning much better once again!
I'm not sure why my pool water didn't work out so well in my spa. While I have been using BBB this year to maintain my pool, last year I used traditional pool store chemicals. So there may have been some residual chemicals still left behind in the pool water that were not so good for the spa. Also, I have added NaCl to my pool water to improve the "feel" of the water. I wonder if the salt was contributing to problems in the spa too. Whatever the reason was though, I don't think I will ever fill the spa from the pool again.
Good luck with your new spa, Rocky! Maybe filling your spa from your pool won't cause you any problems, but I thought I would share my experience just in case.