Adjust TA first, right?

My PH keeps wanting to climb, unless I add acid about once every week or two. Don't have an SWG (wish I did!), and it has rained alot, so can't figure out why. Anyway, in keeping my PH down, I think I have accidently done the "lowering the Alk" procedure, because we run our fountains and bubblers alot too. My Alk was raised up from 80 to 130 about a month ago (PB added baking soda), and it has been creeping down ever since. Now it's 70.

Should I leave PH alone until after I get my TA where I want it? I think I read that somewhere, but can't find it now. If I have a 22,000 gal, vinyl IG pool, how much baking soda should I add? Can I put it in the skimmer? Should I dissolve it first? How long after I add can I do an accurate test, and then add acid to bring PH down?

TA should be adjusted to the appropriate level before ph is adjusted.

Hope this helps,
J.

I would add a lb. of baking soda at a time. Add it slowly to the skimmer while the pump is running. Don't need to predissolve it. Wait a few hours to let it circulate before retesting. I'd aim for an alk reading of 100. How high is your ph?

actually, it can take as long as 48 hours for the TA to stabilizer when you adjust it but you should have a good idea in about 8 or so.

Quote:

---

Originally Posted by Watermom

I would add a lb. of baking soda at a time. Add it slowly to the skimmer while the pump is running. Don't need to predissolve it. Wait a few hours to let it circulate before retesting. I'd aim for an alk reading of 100. How high is your ph?

---

PH is 7.8 to 8.0ish.

I'm going to do as you said. You haven't steered me wrong so far!

You should end up putting about 8lbs of baking soda in (if your pool size and TA readings are correct)

Hope that helps.
Joe

That may very well be true, but I have found with baking soda, it doesn't always take as much as the bleach calc suggests, so I tend to add slowly rather than overshoot the target. Especially since she is already close to the desired range already.

Quote:

---

Originally Posted by cruzmisl

TA should be adjusted to the appropriate level before ph is adjusted.

---

WRONG!

PH should be adjusted first. The reason is that your alkalinity will change, if you adjust your pH, and what was a problem, may not be one, once you fix the pH.

The idea that alkalinity should be adjusted first is widespread in the pool industry. There's even a trademarked slogan, "Alkalinity First!"

Can you guess whose slogan it is?

Hint: The are the largest manufacturer and distributor of sodium bicarbonate, both for industrially, and for retail sales. Hint #2: As I just discovered, they even have a BRAND of sodium bicarbonate called "Alkalinity First"

Can't guess? It's Church & Dwight, owner of the "Arm & Hammer" brand.

But, even if you couldn't guess whose slogan it was, now that you know, I'm pretty sure you can figure out why it's their slogan. I'm SURE it has nothing to do with selling you more baking soda than you need! :rolleyes:

Ben
PoolDoc

See shows what I know. It was just my 2 cents worth of info which is precisely how much it's worth :)

Quote:

---

Originally Posted by PoolDoc

WRONG!

PH should be adjusted first. The reason is that your alkalinity will change, if you adjust your pH, and what was a problem, may not be one, once you fix the pH.

Ben
PoolDoc

---

OK, so If I want my PH to be 7.4 to 7.6, and my TA between 100 and 120, I should add acid first to get my PH down, and then add baking soda to bring my TA up? Should I wait a certain time in between?

I'd just leave ph of 7.8 alone. If it goes any higher, then I'd try and drop it some, but anywhere 7.2-7.8 is OK. And, your alk is only a little low. Go slow with the baking soda.

Quote:

---

Originally Posted by PoolDoc

WRONG!

PH should be adjusted first. The reason is that your alkalinity will change, if you adjust your pH, and what was a problem, may not be one, once you fix the pH.

---

Ben, I have a question. If the pH is high, say arround 8.0, and the alk is low wouldn't it make sense to raise the alk first and then lower the pH into proper range? Lowering the pH first would also lower the alk and then when you raise the alk you raise the pH again. I can understand adjusting pH first if it is low since raising it will also raise the alk and both could end up in the proper range then. I have a good grasp on the chemisty involved but would really like your take on it since the interaction between the two does make it tricky. Thanks!

Update so far:

Last night I added about 3 lbs of baking soda. Tested this morning:

TA 90 (up from 70)
PH at least 8.0, very dark pink (up from 7.8 to 8.0ish)

So this morning I have added some muriatic acid, and then another 3 lbs of baking soda. I'll retest this afternoon to see what my numbers are.

My main objective is to get TA to a number that will prevent the PH from bouncing so much. I add acid, it comes down to 7.2 - 7.4, and then it creeps back up again. I am using tri-chlor when I am on vacation (which has been 2 weeks in the last month) and bleach the rest of the time.

I have been testing for FC and PH mostly every day. Maybe I shouldn't be testing PH so much? I am trying to stay ahead of my water, but maybe I should relax a little? Pool has been blue and crystal clear from day one, except for a little mustard algae, which seems to be much better with the higher level of FC. We've had alot of rain here in the south, so I feel better with a little higher level of FC, around 8 or 9. I must say though, my husband (who knows NOTHING about pool chemistry) is just amazed that I have kept the water looking so good. He thinks I'm a genius, but I know that you guys are the real geniuses!