Update on BBB in spa. I am still using it successfully. Earlier in this thread I had said that I was still getting "white stuff" around the fittings - white and sort of like dry peanut butter in consistency, definitely "growing" over time, plus a somewhat sour smell to the water (very slight). All this was happening with good chems all around, no CCs, good FC/PH/TA.

I tried "shocking" several times to no real avail. I finally tried some Spa Perfect, an enzyme based conditioner. I had stopped using this a while ago when I found this forum as I tried to reduce extraneous chem usage as much as possible. But, I had bought several bottles on sale, so I had it around and decided to give it another try.

Surprise, surprise, it worked GREAT. Not only did it eliminate the "white stuff", the water smells much better (clean and almost odorless) AND the spa just feels cleaner. So, now I am using BBB in the spa with an occasional shot of Spa Perfect.