Need help rebalancing after an acid wash!

[schwimmen]

Hi, all. This is not a very exotic request, but I would greatly appreciate your help.

We had our pool put in last year, and within the first month, there was significant scaling. I thought maybe it was all in my head, but when we had our gunite/Pebble sub come out, the guy could see it right away. They gave several suggestions that might help depending on type of scaling (e.g., keep pH down low and continue to brush regularly), but they didn't help. If anything it was more pronounced. Fast forward to this week... On Tuesday, they came by, emptied the pool, did an acid wash, and did a treatment to address what looked like water trapped in or behind the gunite (dehydration treatment?).

I now need to get the pool rebalanced, and after the first scaling issue, want to get it right and get it done quickly. The sub said that we could go ahead and start the filter and then balance the water - in other words, no special instructions.

Here are the readings I have:
pH: 8.2+
TA: 110
CH: 125
TC: looks to be about 0.5
CYA: no reading

The filter is on, and I added ~3cups of muriatic acid this evening.
Any recs for the order to address the rest? Anything to look out for?

 

[ajw22]

What test kit are you using?

- Add 60 ppm of stabilizer using the sock method
- Add 5 ppm of liquid chlorine and maintain that until your SWG is generating
- Add 3000 ppm of salt with your SWG off and let pump run for 24 hours
- Add 125 ppm of calcium
- Maintain a pH of 7.6-7.8. Add MA as necessary.

You can do all those at the same time.

Tell us what the pH, TA and CH is of your fill water.

What is your pool water temperature?

Use PoolMath to log and share your test results. Enable logging of water temperature and tracking of CSI in PoolMath

Once you add all the chemicals above report your test results and we will move to the next stage of water balancing.

Ask questions if you don’t understand anything.

 

[schwimmen]

We've got a TF-100 testing kit.

The temperature is 68 degrees.

The pH was still between 7.8 and 8.2 when I went to add the other chemicals, so I added 3 more cps of MA and will add the others in the morning.

The pool is approximately 10K gallons.

Based on that, it looks like I add the following:
12 CYA stabilizer pods (says 2 pods raise it 10ppm for a 10K gallon pool)
6 bags of salt
12.5lbs calcium hardness increaser

I have bleach (does not indicate strength), but I also have a 6-in-1 trichlor disk and dispenser. Would it be ok to use that, too?

 

[duraleigh]

Get your pH down into the 7's and keep it there. Scale is most always a result of high pH and you have already seen the results.

What is the pH of your fill water?

Your other chemistry should take a back seat to bringing down the pH and keeping it down. Once you have that firmly in control, work on your chlorine.....I don't see where you have tested it.

Please read "The "ABC's of Pool Water Chemistry" up in Pool School

 

[schwimmen]

Get your pH down into the 7's and keep it there. Scale is most always a result of high pH and you have already seen the results.

What is the pH of your fill water?

Your other chemistry should take a back seat to bringing down the pH and keeping it down. Once you have that firmly in control, work on your chlorine.....I don't see where you have tested it.

Please read "The "ABC's of Pool Water Chemistry" up in Pool School

The pool pH was approx 7.8 so I added more MA. I’ll start chlorine this afternoon. The first chlorine reading was around 0.5.

I just tested the tap pH. It’s about 7.8+

I’ve read the ABCs and have been following it. The scaling happened early, before we took over balancing the water. I want to get it right this time.

 

[ajw22]

The pool is approximately 10K gallons.

Please put that in your signature.

I have bleach (does not indicate strength), but I also have a 6-in-1 trichlor disk and dispenser. Would it be ok to use that, too?

Bleach should say the strength in the ingredients on the label. It is probably 6%. Don't use Clorox bleach which contains Cloromax Technology or belach with other additives.

If you use Trichlor it will add CYA. You should back off on the stabilizer you add and you need to monitor your CYA and stop using Trichlor once your CYA gets around 60 ppm.

 

[JJ_Tex]

I noticed in your pool math logs, you had several additions of calcium over the past year. We typically have hard water, and I would be hesitant to add any additional calcium this time.

PS - Enter your test results in pool math, so you can see how it calculates your CSI.

 

[schwimmen]

Greetings.
I just ran the tests (logged on PM):
TC - 0.5
pH - 7.7
TA - 100
Ch - 125
CYA - did not test, have not yet added any (used 30 as place holder)
Temp - 64 F
Salt - 0 ppm (none added yet)

I added 2 cups of MA.
Do I move to more chlorine now and wait on the rest?

I also want to make sure that my ranges on PM app are correct. They're currently set at:
FC 2-6
pH 7.2-7.8
TA 60-80
CH 350-450
CYA 70-80
CSI -.6 - .6

 

[JJ_Tex]

Your chlorine is low currently, and I would bump up your target FC to 4-6, since 3 is the minimum for a CYA of 70.

Add some liquid chlorine to get it up to range, then add the salt and turn on the swcg.

While your calcium is low (and I'm in the same boat), our water here is so hard that I really dont want to add any calcium so I just keep an eye on my CSI number and try to keep it slightly negative. As it gets colder I've noticed I need to keep my PH around 7.8 to not get too negative on CSI.

 

[ajw22]

CYA - did not test, have not yet added any (used 30 as place holder)

Don't do that. If it is 0 then put 0 into PoolMath. Put your actual test numbers in. PoolMath uses the values in figuring out the chemical doses and there are interactions int he formulas you don't realize.

I added 2 cups of MA.
Do I move to more chlorine now and wait on the rest?

Add your other chemicals. Why do you think you should wait?

I also want to make sure that my ranges on PM app are correct. They're currently set at:
FC 2-6
pH 7.2-7.8
TA 60-80
CH 350-450
CYA 70-80
CSI -.6 - .6

CH can be lower and it will rise over time.

CYA 60 is ok for the winter.

What are your targets within the ranges? The ranges are general guidelines.

 

[schwimmen]

I just checked today's pH and TC. They are at 7.7 and 0.5, respectively, so I added another jug of bleach (assuming lower concentration; no indication of % anywhere on bottle/label).

Today's question: Should I try to drop the TA down (was 100 yesterday)?

Based on re-reading of Pool School, high TA can drive pH up and can contribute to scaling, which I'm trying to avoid this time around. Do I do the 7.2 pH/aeration process until I can get that down, or do I just focus on making sure that the pH stays at 7.8 or lower? It's not clear to me if that will come down on its own or if it will stay high until I address it?

Otherwise, my plan for the day was to see if I can get the chlorine level up to at least 3 or 4, than add salt and turn the SWG back on a day later.

ajw22, based on duraleigh's suggestion to focus first on pH and chlorine, I was thinking I should hold off on adding everything at once. I also feel like I read some threads about unanticipated reactions between chemicals if you don't space out their addition to the water. It would certainly be easier to add everything at once.

Thank you all for your continued assistance!

 

[ajw22]

First of all GET YOUR FC UP! Your FC of 0.5 is never good.

If you don’t know the % of the bleach then put it in the pool and test 30 minutes later. Repeat until you are at or above your FC target. You will then learn how much raises your FC a given ppm.

You have to get stabilizer into the water to maintain your FC. Get that going by the sock method.

Check your pH daily and add acid as needed to keep your pH in the 7s. Trying to reduce your TA can wait.

Salt does not interact with anything. If you want to get your SWG going then start getting the salt dissolving in your water.

 

[duraleigh]

Do I do the 7.2 pH/aeration process until I can get that down

Your pH will tend to continuously rise. As it does, you bring it back down with muriatic acid and that will also reduce your TA. So, I would simply control the pH with muriatic and monitor your TA as it comes down.

You still need more chlorine in your pool. It is the single most important chemical you add and it is constantly consumed so get it up......You must test your CYA to get the correct amount of FC but I can promise you it will be at least 4 ppm.

If the jug of chlorine doesn't tell you the concentration, don't buy it......it's probably 3% or less and not a good deal.

 

[schwimmen]

Okay, making progress.

pH 7.5
FC 4.5
CC 0.5
TA 80
CH 200
CYA undetectable
Temp 64
CSI -.40

I got the chlorine up with a sanitizer/shock. Adding salt so we can get Intellichlor back on line.

The TA has started to come down.

I added 5 lb of CH treatment to start bringing that number up.

CSI is -.40 and it looks like adding CYA without getting other levels in better spot would make that number look worse. Best next step?

Hope you all had a great Thanksgiving!

 

[ajw22]

Add stabilizer and let your pH be around 7.8 to raise your CSI.

 

[schwimmen]

Add stabilizer and let your pH be around 7.8 to raise your CSI.

Ok, will do.