Ph, TA and CH Issues

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Rick T

Well-known member
Apr 28, 2019
139
Houston, TX
Recently I had white patches on my Quartzscape pool. I posted those issues back in a different thread. The pool resurfacing company came out and dumped several gallons of muriatic acid in the pool then tied a recirculation pump (so I wouldn't use my pool pumps) and left it there for a few days. After about 4 days of this, the white spots came out. He then put a few pounds of soda ash (approximately 3 pounds) in the pool to bring the ph back up. It has now been over a week and I did the full gambit of chemical tests and am having issues I haven't seen before.

FC: 7 (14 drops) I use mostly liquid chlorine
TC: 7.5 (added 1 drop R-0871 to bring it clear)
CYA: 50
CH: After adding 10 drops of R-0010 and 3 drops of R-001L I stopped adding R-0012 after 20 drops with little to no change (I did the test twice and stopped after 20 drops both times. The solution never turned blue)
TA: After adding 2 drops of R-0007 and 5 drops of R-0008 the solution never turned green. It was a light red/pink color so I didn't add any drops of R-0009.

My pool is very clear and I think my chemicals were quite balanced prior to them adding several gallons of muriatic acid.

Any help is appreciated.
 
Rick, can you post your current pH? Sounds like the no-drain acid wash removed the white spots (calcium) and made the calcium soluble. So basically the calcium is still there, it's just in the water which is why your CH may seem to be higher on the test. Gotta watch that CSI really close now or it will try to reattach. You should keep going with the CH test until you see a final result (light/baby blue) so you know what you have to work with. If the CH is really high, a partial water change is the only way to lower. Next time we get rains in our region that may help.

I have a feeling your pH and TA are still very low, which is why the TA test seemed odd, but you'll need to post again. If so, you don't want it that way too long for the care of your heater.
 
The TA is zero or lower. The pH is 4.5 or lower.

You need to raise the TA to an acceptable level.

In the calcium test, the first reagent is sodium hydroxide, which raises the pH and causes the magnesium to precipitate out.

When the pH is too low, the magnesium gets measured with the calcium causing an incorrect reading.

If the water has been circulating through the heater, it has stripped out a significant amount of copper, which will eventually cause leaks.

The copper will interfere with the calcium test.
 
Thanks. I will 1st address the low ph. The small blue box ph test was below the color reading. It was yellow. I will guess it was a 6.6. The pool app math says 8 lbs of soda ash. That seems like a lot. Better to drop the water level 8-10" and then refill first?
 
Here's what I've done so far. I took a sample of water to Leslie's. They first detected copper in the water and said that it needed to be addressed. I bought this metal free product. I have poured that in the pool. I have also added approximately 4 lbs of soda ash. The pool is quite milky now. I will retest the water tonight. I also plan to run the pump continuously until I get this figured out.

bottle.jpg
 
Now is the time to make a decision, keep following the pool store and dropping lots of money there or follow our methods. Not much credence is given to pool store testing around here. While you would think that a "professional" would be the best, unfortunately in most cases it is quite the opposite. Between employees who blindly trust the word of chemical sales representatives and high school kids working in the pool store for the summer you end up with poor results from their testing. Plus, the results of their "testing" is used to convince you that you need to buy things. Why do you think that testing is free?

In this case, they won. The redirected you to a "problem" you didn't know you had and made a sale. Did that problem exist. Probably not.

The problem you do have you are not addressing as we are advising. Raise the TA to 60 with baking soda. Once there you can address the pH.
 

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Rick T said:
Do baking soda and soda ash do different things?
Click to expand...

Yes, they do. Baking soda raises TA with minimal effect on pH

I would add 6 pounds of baking Soda which should raise the TA by 24 in your pool.

Each pound will raise the TA by 4, so once you get a good reading you can calculate how much you need to get to 60.
 
Rick T said:
Thanks, Tim. Since I don't have an accurate starting point (test was faulty), how many pounds should I start with to bring it to 60?
Click to expand...
As I said, add 6 pounds of baking Soda which should raise the TA by 24 in your pool. That should get you to a point where you can measure it.

You want to go slow, not dump in too much and overshoot.
 
Dumb question here, but if the white spots are gone which has caused the CH to go through the roof, why not dump the water now and do a fresh fill. We dont want the CH to precipitate again causing those white spots to come back.
 
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