Pool refilled-low pH and high TA

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Enumjon

Enumjon

Well-known member
Apr 30, 2020
105
Tijeras, NM
Pool Size
25000
Surface
Plaster
Chlorine
Liquid Chlorine
Hello there! Brand new TFP member. Bought a house last summer with a pool-my first ever. I kept up the previous owners regimen of tricolor tablets with regular powdered shock and regular clarifier and algicide to keep the pool looking nice. Luckily in my web browsing this winter I discovered this site. Once the pool was opened this spring pool store testing affirmed that I needed to drain the pool and start over-no surprise considering the previous regimen.

The pool is about 35k gallons, gunnite, sand filter. I drained the pool, did a little acid wash to remove bad mineral deposits, and just filled up the pool. The only thing I have added is a little chlorine to keep the algae down while I test and figure out chemical levels.

Today’s readings from my brand new TF-100 kit, with pH tester. PH 6.0, CYA 0, FC 3.5, CA 1875, TA about 600 (I was getting close and didn’t want to waste more reagent).

My plan was to use muriatic acid to reduce the TA and borax to raise the pH, with the nice side bonuses that borax gives the water. But with that sky high calcium reading I am afraid that plan may be out the window. Can those readings even be correct? Our water system currently has a hardness reading of 32 grains. Any advice would be greatly appreciated.

Jon
 
As I stated in your other thread, is this water used for human consumption? Do you have a water softener for your home?

The TA, pH, and CH look really suspect. I bet you have some metals interfering with your results.

Matt - @JoyfulNoise - are these results reasonable for a potable water?
 
Yes, we drink this water.
Yes, we have a water softener.
I was worried that some chemical may be off and throwing the other readings out of whack.
 
Let's see what Matt says -- but I do not believe you should use that raw water in your pool. You may want to see about trucking in water and using your softened water for makeup.
 
I already looked into trucked water, it is a no go. Down in Albuquerque there are not any water trucking companies. Up here in the east mountains all the water trucking companies draw from the same water company we use, and cost 10x our regular water.
 
Can you either measure the pH/TA/CH of your outside fill water (not from the softener) or post a water quality report from your water supplier. Your test numbers don't make a lot of sense. 32 grains per gallon is 528ppm calcium hardness. That is certainly possible in some parts of the US, especially if the well water is drawn from an aquifer in contact with dolomite, but I'd like to confirm it and also see what the raw water source alkalinity is.

For example - with a TA of over 600ppm, your pH wouldn't be nearly that low. Are you sure you did the TA test correctly - added R-0007 and swirled, then added 5 drops of R-0008 and then titrated with R-0009 until the color stop changing? Also, are you holding the R-0009 bottle absolutely vertical and letting the drops fall from the tip (maximizing droplet volume)? It helps to use a SpeedStir when doing these tests especially if the droplet count is going to be that high.

Do not use Borax to raise pH and muriatic acid to lower TA, you'll only go on a merry-go-round chasing pH. If your pool water pH is truly that low and the TA is truly that high, then you need to aerate your pool water to raise pH and then lower the pH using muriatic acid. That cycle will have to be done many, many times to get the TA down to any reasonable level. If your CH is as high as you report (is that really 1875ppm?), then your water will cause major scaling. Your tile should have a nice white crust all over it.

Also, how did you get a CYA of zero?? If you were using trichlor tablets and powdered shock, you should be seeing some CYA in the water.
 
Joyful noise, I did the testing again fully inverting the bottles as you said to maximize drop size. Also I had not calibrated the electronic pH tester, and it was way off. The new numbers are:

pH 6.9 for both pool and hose water
TA 650 for pool, 550 for hose
CA 1200 for both pool and hose

CYA is zero because I just refilled the pool. I thought that CYA would have absorbed into the plaster and then leached back out into the clean new pool water, but apparently my wall cleaning took care of that. Or maybe it has not been long enough to leach out, it has only been 24 hours since it was filled. Anyhow, the view tube only goes down to 20, and it was easy to see the black dot with the tube completely full.

And yes, our water system draws from wells that are full of all sorts of minerals. Everything with non softened water is coated in a nice whitish coat, from the pond to the swamp coolers.
 
CYA does not leech into the plaster. That is a myth.

You need to add CYA.

That water will be a challenge ----
 
It may just be coincidental, but all results for TA tests have been multiples of 25. Just want to ensure that you are multiplying drops by 10 and not 25.

I hope you get things sorted out. Good luck.
 

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You are going to need to lower the pool TA using the acid/aeration process. You aerate the water (fountains, jets, spillover, etc) until the pH reaches 7.6 on it own and then you add enough acid to drop the pH down to 7.0-7.2. You then start the aeration again. You keep doing this until your TA gets below 100ppm. It’s going to take a lot of time to do this so just keep at it. In the meantime you should get your CYA up to recommended levels and get the FC up. Use only liquid chlorine to chlorinate - do not use any pucks, powder or magic potions.

www.troublefreepool.com

Lower Total Alkalinity

A lower Total Alkalinity level can help a pool owner stabalize their pH increase. We'll explain how to lower TA with a little help from muriatic acid.
www.troublefreepool.com www.troublefreepool.com

Also, you are going to want to get creative in covering the pool and limiting water loss to evaporation. You do not want to keep adding that hose water to the pool as it will only raise the TA and CH strongly. You might consider getting an RV style water softener to run your hose water through when filling the pool that way you can at least eliminate calcium hardness from the fill water.
 
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Hi all, thank you very much for your advice. And yes, I multiplied by 10 for the TA test, 25 multiplier for the CA test. Looks like my current plan is to get CYA levels up to about 50 and do the aerate/muriatic acid process to lower TA. The aeration is not great on my pool-I can only use the spa waterfall since the returns are to deep to disturb the surface.

Long term I have a few ideas for dealing with the CA. In the winter months the wells in our water system are being recharged with snowfall, so the water hardness levels drop significantly. In January the water hardness was down to 12 grains, compared to our current 32. Would it be a good idea to do a partial drain and refill in the winter, even though it is 10 degrees out? I also like the idea of rain diversion to the pool, we usually get summer thunderstorms that drop significant rain in July and august. And minor refilling of the pool I can do from a utility sink in the laundry room, since that is softened water. Is it going to be a problem putting all that salt in the pool? We use potassium salt in our softener. And one last question-with my mineral numbers where they are is it a bad idea to add borax to bring the borate levels up to comfort levels?
 
You do not want add borates to the water at this point otherwise it will take A LOT longer to lower TA. Borates act as a buffer against pH and will slow the pH recovery for the aeration part of the process.

The main focus is getting the CYA and FC correct then deal with the TA, that’s it. Don’t worry about anything else.

By the way, swimming and splashing is a great way to increase aeration. So if you can, get people playing in the pool while you’re lowering TA
 
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