Hot Tub balance question - Jacuzzi J345

[orion6192]

Question... I’ve been using the bleach dichlor method for the last 5 years - entire life of the tub. I read nitro’s water balance many times and think I’ve been doing it right... or at least almost right.

Jacuzzi J345 340 gallons

I take my initial readings and plug them into the pool calculator and dial to zero or as close as possible.

Where my my second guessing is coming in is it says to add dry acid until you get to 7.0 - 7.2 and then aerate again. But if I keep acid every time I’ll bottom out my TA trying to get my PH down.

So I run all the jets, PH is usually 8 or even higher after aeration. When should you actually read the PH? Right after the aeration cycle or let it sit. If I check it after it aeration it’ll be 8 if I check it with no aeration as it’s been sitting it’ll be 7.7.

My my initial numbers were this: Fresh Fill - Ahh-Some purge 11/24/18

TA 200
CH 180
PH 7.5
CYA 0
Borates 0

My target TA was 80 if I follow the csi close to 0.

TA 80
CH 180
PH 7.7 (non-aerated)
CYA 7.8
Borates 0

It just feels like I’m missing something fundamental with the balancing. I’m usually around 65-70. But again I have never driven the TA down to 7.0 and then Aerate up to 8. It would seem that the water sits more non-aerated than aerated and would have a ph down in 7.0 to 7.2.

Someone willing to pull my head out of the weeds on this one? Greatly appreciated!

 

[jseyfert3]

Adding acid to get your pH to 7 and aerating is how you lower your TA from a really high amount (200 for you, 250 for me) to get it close to 50. Once your TA is getting close to 50, stop targeting a pH of 7. Start targeting a pH of ~7.4-7.5, and once your pH remains stable somewhere around 7.4-7.8 after aeration, you're done. This varies based on water supply but typically happens around a TA of 50.

Another thing to note is don't worry if you CSI is negative. Negative CSI has zero concern for a fiberglass or vinyl spa or pool, it's only a concern with stone/gunite spas or pools. Negative CSI won't corrode metals, it just dissolves calcium out of stone/gunite. pH is all that really matters for metal corrosion, if it's above 7 it should be fine (and 7 is lower than you want anyway). That's where the 7 comes from when adding acid to lower TA. It's just the lowest you want to bring the pH to avoid damage to heaters/etc.

Hope this helps!