When to increase Total Alkalinity in Hot Tub?

[BigOrangeSpa]

Hey ya'll,

Had a quick question I was thinking about as I was adding some acid tonight to lower my pH. First, here's my latest test results:

FC: 4
CC: 0.5
pH: 7.9
TA: 60
CYA: 30
CH: 150
Borates: 50

When I use the effects of adding tool in PoolMath, I can see that the 1 oz of MA I added to bring pH down to 7.6 is estimated to bring TA down by 9. If I do this a couple of times, my TA will presumably be below 50. I was curious if when I'm approaching the lower end of the acceptable TA level (I've heard it could be as low as 40) if I should go ahead and add enough baking soda to offset the TA decrease shortly after adding the acid. Or if there's another approach I should follow to make sure TA doesn't get too low while adding acid to lower pH.

I guess another question is if I'm finding my pH is pretty stable at 7.9 if I even need to try to bring it down to 7.6? The sticky says 7.8 is the max so that's why I've been trying to keep it under that and closer to 7.6.

 

[Gebo]

In my experience, I don’t think dropping the pH that small amount will do much at all with the TA. I’m pretty sure the more knowledgeable advisors on here will tell you that with your borate at 50 don’t worry about pH until it gets to 8. The borate pushes the pH up naturally.

 

[BigOrangeSpa]

Thanks @Gebo!

If I understood the sticky correctly, Borates were used and 7.8 seemed like the upper bounds of acceptable pH. Maybe that's just outdated advice at this point. It does seem like a lower pH would be more comfortable but at the same time, I'd rather have a slightly more uncomfortable pH level than chasing it all the time. Haha, this hot tub has been a lot more work than I anticipated but it is fun.

 

[Gebo]

On my previous fill, I know that I kept trying to get pH down to 7.4 and it kept going back and settling 7.8. With the borate being at 50.

This current fill has stabilized at 7.6 this first month.

Go figure.

You are probably too much like me. Striving for perfection!

 

[Mdragger88]

Any ph in the 7’s is equally fine.
Letting it ride all the way to 8 before taking action is fine.
Once ta is around 50 you’ll likely notice a much slower ph rise especially with borates involved.
Do not preemptively add baking soda this will just put you on a merry go round with ph & ta.
Baking soda is only needed if you actually go below 40 then add enough to get to 50.
My ta is generally 50/60 and when i add acid to go from 8.0 to 7.6 - 7.8 there’s no noticeable effect on ta.

 

[BigOrangeSpa]

Many thanks to both of you, I will go ahead and just monitor TA if I add acid and only adjust when it's going below 40.

 

[Gebo]

I’d listen to anything mdragger88 says (about hot tubs)

 

[Mdragger88]

I’d listen to anything mdragger88 says (about hot tubs)

There’s alot I don’t know but I do understand the ph/ta dance and a bit about resisting the urge to micromanage!

 

[Gebo]

Wisdom speaks.