Wanting to add borates - is my TA too high?

[Mikki]

I would like to add borates to my pool, but I have been attempting to lower my TA first. Here's where I'm at now (using TF-100 kit):

Pool - 13,000 gallons inground, pebbletec, SWG
pH - 7.5
TA - 120
CH - 330
TC - 4.5
Salt - 3900
CYA - 90

I checked my fill water, and the TA for it is 200 . Should I try to get my TA around 60-80 before adding borates, or should I give up and just do it?

Thanks,
Mikki

 

[Guest]

IMHO, if you are adding borates to help buffer pH changes then getting your TA into range is important. If you are simply adding borates as an algaestat then it really does not matter.

 

[Mikki]

No, it's to help buffer the pH rise with the SWG; I've been adding acid about every day or every other day... I guess I should just keep adding acid until the TA gets to 80 or so? What's the most acid I can safely add at one time?

 

[Guest]

No, it's to help buffer the pH rise with the SWG; I've been adding acid about every day or every other day... I guess I should just keep adding acid until the TA gets to 80 or so? What's the most acid I can safely add at one time?

Unless you have an acid demand test it's just about imposstible to tell since the TA wil play a part here BUT I would suggest no more than 1 qt per 10k gallons and then check the pH in 30 minutes. Stope when the ph is around 7.0 and then aerate to bring the pH up (You only realy need to bring it up to about 7.4 before adding more acid, btw.). Repeat until TA is around 70 ppm. The slow part of this process is the aeration to bring the pH back up so the better you can aerate the water the faster it will go.
(When adding acid to only adjust pH and not TA I would not recommend more than 1 pt. per 10k gallons.)

 

[chem geek]

It will take a cumulative total of 16.6 cups of full-strength Muriatic Acid (31.45% Hydrochloric Acid) to lower the TA from 120 ppm to 80 ppm in your 13,000 gallon pool. Of course, you don't add that all at once. You first lower the pH down to 7.0 from where you are starting which would take 7.2 cups of acid at which point you would then aerate and add more acid when the pH rises following the Lower Total Alkalinity procedure.

You can use The Pool Calculator for a rough estimate -- it said it would take 49 ounces (6.1 cups) to lower the pH to 7.0 which is a little low than the "accurate" theoretical number, though not bad. Jason updated the calculator to take into account the TA as well as Borates for estimating the amount of acid needed to lower the pH.

As waterbear is pointing out, you don't want your pH to get too low so you can add acid in careful limited increments to be on the safe side.

Richard

 

[Mikki]

I've been working at the TA today... Using an aerator and running the pump (SWG aerates some too IIRC). I added 1/4 gallon of acid (I think it's only 14.5% tho :x - need to pay more attention to the strength when buying it next time!) and then checked the pH about an hour later and it was 7.5 again, so I added another 1/4 gallon of the acid. I'll check the pH again in another half hour or so and see how it's doing... I will also need to add more acid when I add the borax, right? Guess I should pick up some of the stronger stuff .

 

[frankgh]

I,m in the middle of doing the same thing, here is what I started with:
FC 2.75
TC 3.25
PH 7.8
TA 120
CH 350
CYA 50
Salt 3800

I put a gallon of MA in yesterday, it got the PH right at 7.0. Today PH is back up to 7.6 but TA only drooped about 10 points. I know I need to shock too but I was waiting till I sort this TA out first so PH reading would remain accurate. I just re dosed another gallon of acid so I guess we will see tomorrow how the TA came out. I want to ad the boric acid next week.

Anyone have an idea why the TA did not drop the 25 so point the pool calc said it should have?

Oh, I forgot: 22,000 gal gunite pool, 1 year old. SWG added 2 weeks ago. Test for PH and CL, ColorQ, Taylor for the rest.

 

[Mikki]

So far, I've added 1.25 gallons of the 14.5% muriatic acid with the pump running and aeration. Most recent pH check was around 7.0 and my TA is now down to 90. I'll keep it up until it's down to 60 or so. When I moved into the house in October the TA was 240 - so I've come a long way!