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

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iamcparsons

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Jul 18, 2010
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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 do I know when the water is safe for the kids?...would it be easier and quicker to empty/refill?

Thanks so much for any advice!
 
Hi Frustratedpoolmom,

Thanks for your response. The active ingredient in the pH plus is sodium carbonate (98%)...do you think it would do? or should I follow Bama rambler's borax suggestion.
Also, could you tell me how I can know when the water is safe for the kids?
 
That is soda ash and it will raise your TA too much. Use Borax instead.

The water's not safe for swimming if it's cloudy or if the chlorine is 0. Sounds like you have no CYA or chlorine in the pool? You need to bring these other parameters into range before they can swim. Do you have any stabilizer/CYA on hand? What about liquid chlorine?
 
What would I do without you?!
I have been adding bleach about once a week (this is how long my 12'x36" round pool has been up), but because of the high alkaline, it was being canceled out..or so i was told.

Anyway, this is what I have on hand...I'll buy Borax today while I am out for the pH...will any of the below work for the chlorine or should I pick up some more bleach or something?

also, can I add the borax same time as chlorine product or do I need to wait for a period of time?

I have:
Sock it- shock 'N swim: calcium hypochlorite 47.8%

Chlorinating granules: calcium hypochlorite 47.8%

Stabilizing conditioner/balancer: Cyanuric acid 96%


Thanks again, I really appreciate it!
 
(this same question was posted on another forum and I repeat my response here)

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, but still very high close to where you started). 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 TF-100 because test strips can be inaccurate.
 
You are right,I did post the same question at swimming pool help forums...thanks for your response...I don't have a way to aerate the water, so I just got back from the store with supplies, including the borax and bleach. I used the wizard (nice!) and now I am just not sure in what order to add my Borax, bleach, and whether I should plan to add Cyanuric Acid.

If left to my own devices, I would add the borax now and add the bleach once the pH tests out at 7.2-7.5 (I am using 6-way test strips for now). After chlorine/bromine tests out at 1 & 2 - 4& 6 respectively, I would add the Cyanuric acid...would this be the right way to go about it?

Thanks again for your help
 

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Don't wait on adding at least some chlorine and some cyanuric acid. An easy way to add both chlorine and cyanuric acid at the same time quickly is to use Dichlor -- just don't use too much. With Dichlor, for every 10 ppm Free Chlorine (FC), it also increases Cyanuric Acid (CYA) by 9 ppm. If you don't have that, then just use what you have (according to The Pool Calculator) and use some 20 Mule Team Borax to raise the pH at least to 7.0 to start with, though that will still increase the TA (unfortunately, but at least not as much as pH Up would).
 
You can add them one after the other, but wait at least 10 minutes between each addition, assuming you are adding each slowly over a return flow with the pump running to ensure thorough mixing. You may need to lightly brush the side and bottom of the pool where you add the chemicals. Note that if you are adding cyanuric acid, it is slow to dissolve and will lower the pH -- it is either put slowly in the skimmer to get caught in the filter (which you do not backwash or clean for a week) or you can put it in a sock or panty hose hanging over a return. Since that takes time, you would add your other chemicals first. Until the CYA gets into the water, the chlorine loss will be faster so you'll need to watch that and add more chlorine as needed (that's why I suggested Dichlor instead, but it's OK to go with what you've got).
 
Hi again,
Well I added the Borax, then some bleach--after which I took a water sample to my pool store...the results for pH and TA where
180 TA
pH 7.2.

The person at the pool store told me to add a cup of pH minus, wait 8 hrs, then to ad a cup of baking soda, which I did yesterday and this morning. After testing 2 hours ago, the results where 7.4 pH and still 180 for TA so I added about 7 oz of Calcium Hypochlorite.

My question is whether I am safe switching back to bleach for my chlorine (my water is still testing out at 0 for chlorine)...I still have not added the CYA stabilizer.

Also, how long after getting a reading within acceptable limits should I make my kids wait to get into the pool? I feel like I have a chemistry experiment going on in my back yard :)

Please tell if am I totally off as to what I should do next since my (12 round x 3') pool water is looking cloudy. Would you just drain and start over if you were me?

I tested the water from the hose:
TH = 200
FC/Bromine = 0
pH= 7.8
TA= 180
cya = 0

Thanks so much for your help everyone!
 
iamcparsons said:
The person at the pool store told me to add a cup of pH minus, wait 8 hrs, then to ad a cup of baking soda, which I did yesterday and this morning.
Click to expand...
This is ridiculous advice from the pool store and if you are going to continue to follow their advice you are likely to run into even more problems. The pH Minus would lower both pH and some TA, but the baking soda would raise the TA level and your TA is already too high to begin with. If I assume 2500 gallons, then the cup of pH minus would lower the pH to 6.96 and the TA to 166 while the cup of baking soda would then raise the TA to 184 with little change in pH (to around 7.00). The rest of the pH rise you are seeing is probably from carbon dioxide outgassing because the TA is high (or is test error since it takes time to get the sample to the pool store). You should not be adding baking soda or pH Up products given your high TA level.

You really need to get your own good test kit such as the TF-100 or the Taylor K-2006. You can compare the kits here where the TF-100 has more volume of reagents in a more logical assortment of quantities. With a good test kit, you can get accurate test results and can then get a better handle of what is going on in your pool.

The 7 ounces of Cal-Hypo you added could have increased the FC by 13 ppm (it depends on the concentration of the Cal-Hypo you used). Without any CYA in the water, sunlight can cut the FC in half every hour. Also, the test kit you or your pool store are using may not measure FC above 10 ppm accurately and may think the FC is zero when it is actually high. You should get your own test kit to know what is in the water, but if you really believe that there is no CYA and you have never used stabilized chlorine (Trichlor or Dichlor) since filling the pool, then add some CYA to the pool (you can use Dichlor to do this if you haven't already bought some CYA). You can then use bleach to chlorinate.

Of course, with such a small pool, if water isn't too expensive for you then you could just dump the water and start over (since the cloudiness could be algae already starting to form and you don't have a good test kit on hand). Please read the Pool School including the article on the Beginner's Guide for Seasonal/Temporary Pools and note that if you want to use a less expensive drop-based test kit, you can, but do not use test strips and do not trust the pool store for your readings.
 
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