I have a pool and spa with overflow. We just closed the pool and have the spa open. I want to continue using the BBB method. It looks like I should add some borax to increase my Borates to 50ppm according to Chem Geek from a previous post. Is this right?? The pool calculator indicates 51oz borax and then 25oz of muriatic acid. Is this a good plan?? My TA is 120ppm right now. I only keep the hot tub open for another 2 months into December. My spa is 900 gallons.