Help me understand PH relation to Alkalinity, problems adjusting both


New member
May 10, 2020
Ottawa, canada
Hello all,

Fairly new to all this, bought a house with a hot tub and a pool.

If I understand correctly, these two are true
  • adding PH-DOWN will lower Alkalinity as well
  • adding ALK-UP will raise PH as well
So what is one to do when the Alkanility is ok but PH is too high, it seems I will lower Alkalinity as well and then I will have to add ALK-UP which will raise PH too high again , seems to be caught in a loop.

Thank in advance.


Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
Bedford, TX

TA is the last thing to ever worry about. As long as it does not drop below 50 ppm, you are just fine.. Do not try to get a specific TA number except to keep it 50 or above.

Just worry about your pH.. Since you have a SWCG, then I would run the pH at about 7.8. When it gets to 8.0, drop it back to 7.7. The lower you try to make pH go, the lower you will drive your TA..

We never recommend using pH up and down.. Most of us us Muriatic Acid (MA) to reduce our pH.

As long as your pH is relatively stable, then it does not matter what your TA is..


Jim R.


Gold Supporter
Jul 2, 2018
Austin, TX
It’s best to ignore product marketing names, and just look at the ingredients. Or best yet, stay out of the pool store.

Muriatic acid is the preferred product to use to lower PH. If you lower it low enough, it will gradually bring TA down too.

Baking soda is used to increase TA. It has limited direct effect on PH, but a higher TA leads to a rise in PH over time.


TFP Expert
LifeTime Supporter
Jan 6, 2010
San Dimas, CA (LA County)
Welcome :wave:

ALK-UP is just baking soda with an inflated price and fancier packaging. It may raise pH slightly when added and over time, high TA pushes pH up. pH Down is acid, and it does lower both. There's probably also a pH Up, which will be washing soda under a different name and also with an inflated price. The way to get off the see-saw is to stop micromanaging. That is the pool store's way of selling lots of product. Is your TA above 50 but below, say, 100? Then leave it alone and only worry about pH. Is the pH somewhere between 7.2 and 8? Leave it alone. Is pH above 8? Then lower it. Don't arbitrarily pick some target number and fiddle endlessly with things to achieve "balance" There's a good chance it already is balanced.

Have you used PoolMath yet? There's a thing at the very bottom called Effects of Adding Chemicals. Let's say your pH is 8 and your TA is 80. You target 7.6 ph. It gives a dose. Go down to the bottom and see what that dose will do to TA. It'll go down by 3. Can you even tell a difference between 80 and 83 on the TA test? As an aside, the pH change down at the bottom will be wrong except within a very narrow set of parameters. But the TA reduction will be right.

Do some reading. Start at ABCs of Pool Water Chemistry Do your own testing and pay attention as you're adding stuff. Soon things will make sense and you'll realize that pool chemistry is actually pretty easy.
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New member
May 10, 2020
Ottawa, canada
Thanks all for the tips, I'll stop worrying about TA then. So if I understand correctly, as long as it is above 50ppm, I'm good. Any level which is too high that I should worry about although I'm guessing it's would probably mean PH would be too high as well in which case I would lower PH and it would lower TA.

Yes, I've downloaded PoolMath, I'll start using it. I'll also read up on ABC of pool chemistry.

I'll try to stay away from Pool Store :)

Thanks again.