Did I add too much Muriatic acid to my pool water?

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
iamcparsons
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My Pool: 12' round x 36" intex
Location: Mid- Michigan

Did I add too much Muriatic acid to my pool water?

Postby iamcparsons » Sun 18 Jul, 2010 07:53

Hello, after my 12'ft round by 36"deep pool (about 2000-2050 gallons?) Intex pool had been testing alkalinity out off the chart of my test strip with zero chlorine registering and everything else within acceptable ranges, I called my local pool store who told me to add 61/2 pints of Muriatic acid.

I added 12 cups, which works out to 6 pints. After some reading online, it sounds like most people add only about 3 ounces of the stuff but after testing this morning,
Ph looks like it's 6.4 or less;
Cya is less than zero;
and Alkalinity is around 120.
chlorine 0
hardness 200

Plus since I was afraid to put the pool cover on all that acid -- the surface of the water looks like a bunch of grainy specks, along with insects floating on top. What should I do now and how can I know when the water is safe for the kids?

Thanks much


lbridges
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Location: Space Coast, Florida

Did I add too much Muriatic acid to my pool water?

Postby lbridges » Sun 18 Jul, 2010 11:52

The water is way too acidic - kids would probably be complaining about their eyes burning.

The best way to handle this would be to aerate the water (like with a pool fountain or waterfall thing) until the pH got back around 7.0 before swimming. This would raise the pH without also raising the TA (which is slightly high). If you simply can't wait then use some borax (yes 20 mule team stuff from walmart), or soda ash (arm and hammer laundry booster - NOT A&M detergent). These last two will also raise the TA too, but would get the kids in the pool quicker.

CYA can't be less than zero, so I'm assuming you mean none is in there. You would need enough CYA (stabilizer) to get to around 30ppm, then add enough chlorine to keep the pool sanitized.

There is an online calculator that you can use to help know what to put in a pool. Make sure you change the gallons at the top to reflect the size of your pool.

You really should get a good water testing kit as the pool stores generally can't be trusted and the strips sometimes read rather wildly. For example, my local store's last three tests for calcium hardness ran like 350ppm, then 200ppm, then 400ppm. On my home test kit it is around 400 (I have to get it tested monthly to keep the plaster warranty in force), so they got it right once, close once, and a big miss once - they also had TA numbers all wrong. That one big miss and they wanted me to add about $30 worth of stuff that was solely due to their testing error.
chem geek
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Did I add too much Muriatic acid to my pool water?

Postby chem geek » Sun 18 Jul, 2010 12:06

(I wrote this while lbridges posted; his advice is good)

It's about 2500 gallons if the actual water depth is 36" (3 feet). You didn't say what off the charts means -- that is, what is the highest reading for TA on the test strips? LaMotte InstaTest reads up to 240 ppm so I'll assume your TA was at least that. Assuming your pH started out at 7.5, adding 12 cups of full-strength Muriatic Acid (31.45% Hydrochloric Acid) to 2500 gallons would lower the TA by 150 ppm down to 90 ppm if you started with 240 ppm and the pH would be lowered down to 6.0 which is too low. In practice, some outgassing of carbon dioxide could have the pH be somewhat higher. Since your TA ended up at 120 ppm, you actually started with 270 ppm, not the 240 ppm I assumed. That would have your pH get down to around 6.1 to 6.2 assuming you started with 7.5.

Since your TA is roughly where you want it, but the pH is too low, you need to aerate the water to raise the pH and given how low it is with the TA still at 120 ppm this should take about a day. Point the return(s) upward and have the pump on high (if it is multi-speed; probably not with an Intex pool). If you have a fountain or other device that can aerate the water, use it. If you have an air compressor with a nozzle that produces tiny bubbles, put that into the pool. Obviously, keep the cover off the pool.

If you instead add a base such as pH Up to the pool to raise the pH, it will raise the TA as well, to even higher than you started (if you use 20 Mule Team Borax, it will raise the TA by half as much). Though a pH around 6 isn't good, it isn't going to corrode metal in days so you've got some time to get the pH higher. When the pH gets to at least 7.0, then you could go in swimming -- 7.2 or higher would be better but that could take longer.

You should really get your own good test kit such as the Taylor K-2006 or the TF-100 .

It appears that you also asked this same question on Trouble Free Pool .
iamcparsons
Pool Newbie
Pool Newbie
Posts: 2
Joined: Sun 18 Jul, 2010 07:38
My Pool: 12' round x 36" intex
Location: Mid- Michigan

Did I add too much Muriatic acid to my pool water?

Postby iamcparsons » Sun 18 Jul, 2010 15:42

yes, I did. I was not sure if anyone would respond at all, so I felt compelled to try both places...it is very helpful that you responded, but I don't have an aerator. Instead, I'll do the borax and cross my fingers....I did reply to your post at the other forum at trouble-free pool because now that I think I have the stuff needed, I am lost as to the sequence of adding them. Did you see it?

Ps..I loved the wizard!

Thanks a Bunch :D

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