Quote Originally Posted by bucky4835 View Post
Thank you for your response. I did add CYA right after I refilled the spa. I the only issue is I added a bit more than 30 ppm. I am at 45 ppm. I do keep the TA at the low end. It is at 70 right now but I have been lowering gradually. Im trying to get a feel for where the parameters need to be to stop the ph bounce. So far, as far as adding the bleach, I have been adding close to 9 oz every week. That is using the spa 3-4 times a week with both my kids, and keeping the temp between 100-101 degrees F. Also, the capacity of the spa is 450 gal. Any help or comments is greatly appreciated. Thank you.
45 ppm CYA is OK. I usually recommend around 30 ppm (initially I recommended around 20 ppm), but you're probably fine up to at least 50 ppm. We started to see possible hot tub itch incidents with longer Dichlor use, but it was hard to determine whether that was at 100 ppm or some other specific level so I've been conservative to just recommend relatively low CYA amounts.

9 ounces of 6% bleach in 450 gallons would be 9.6 ppm FC. If you are using the spa 3.5 times with 3 people for 30 minutes, then that is 5-1/4 person-hours and would normally require 26 ppm FC to oxidize the bather waste. Since you are using substantially less and apparently maintaining a chlorine reading, do you have an ozonator? That would explain why you aren't using as much chlorine with frequent usage. Usually it would cut down required chlorine amounts by about half while in your case it seems to be cutting it down to 1/3rd.