Steven Poe

@Scuba JulesSo the current MDS lists the 70 to 80 % Chemical as Boric Acid and the 20 to 30% Chemical as Tetraborate Pentahydrate. Each of these chemicals is listed in Pool Math under the row for "Borate". My readings before starting starting were FC=4.5, Ph=7.6, TA=50, CH=130, and CYA=30 for my 350 gal Spa. I thought I would start conservatively and try to add enough Gentle Spa for 30 ppm Borates. If you put 30 ppm as the goal starting from 0 ppm for my spa; it lists using 8.6 oz for Boric Acid alone -or- 5.0 oz of Tetraborate Pentahydrate alone. I also noted that only the TPB portion needed to adjusted with muriatic acid. So assuming a 70% BA / 30% TBP ratio in the Gentle Spa mixture and playing with the math, 7 oz of Gentle Spa would yield a Boric Acid portion (4.9oz), which provides 17.1 ppm borates and also a Tetraborate Pentahydrate portion (2.1 oz) which provides 12.6 ppm borates. This totals to 29.7 ppm borates, which with the 70/30 ratio was the maximum borates I could expect from the 7 oz of Gentle Spa. So, not wanting to overshoot the amount of acid needed, the assumption is then, that the Gentle Spa is at an 80/20 ratio (lowest amount of TBP). At that ratio, the TBP in 7 oz of Gentle Spa would account for 8.4 ppm of borates which Pool Math lists as requiring 1.6 oz of Muriatic Acid (roughly 10 tsp). First shot with this ylelded a Ph = 7.6 and TA =60 and I'm good.