Low pH and High Alkalinity

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
Ed

Low pH and High Alkalinity

Postby Ed » Mon 28 May, 2007 11:11

My pool water is cloudy. The pH is low, but total alkalinity is very high - almost off the charts. If I add soda ash to increase the pH, the alkalinity will also go up. If I reduce the alkalinity by adding acid, the pH will go even lower. Any suggestions?


Buggsw
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Postby Buggsw » Thu 31 May, 2007 00:10

You can use 20 Mule Team Borax to raise your pH without raising your TA.

You should also aerate your pool by running your pump 7/24 and using anything that would make your pool water get more air. A waterfall, fountain, turning the return jets upwards. Anything that will cause more turbulence to the water or droplets. The more water that get's air, the better. This will raise your pH without raising your TA.

Once you get your TA up to the mid to high of the recommended range, then use Muriatic Acid to lower your pH down to 7.2, this will also lower your TA. When your TA get's down to 7.2, then aerate to bring the pH up again. It will take several treatments over several days to lower your TA.
savannah

Low pH and High Alkalinity

Postby savannah » Tue 23 Feb, 2010 13:11

I have a 60,000 gallon plaster pool. My pH is 7.3 and total Alkilinity is 170. What can i do to lower total alkilinity and raise the pH?
chem geek
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Low pH and High Alkalinity

Postby chem geek » Tue 23 Feb, 2010 21:26

First of all, you may not need to lower the TA if your pH isn't normally rising. If it tends to be low due to use of Trichlor tabs/pucks, then realize that for every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm. If your Calcium Hardness (CH) is low and your pH isn't rising over time, then you can probably just live with the higher TA as it provides some more pH stability, though the continued use of Trichlor will be a problem at some point if you don't use an algicide or dilute the water to reduce the CYA level. If you still want to reduce the TA, you follow the procedure described in this post.
Guest

Low pH and High Alkalinity

Postby Guest » Mon 23 Aug, 2010 18:24

My pool holds about 35,000 gallons of water and my TA is about 45 drops to clear teh blue liquid in the test. My pool store says worry about it. Seems odd to me. Why test it? I also have an algae problem at times. My chlorine is very high all the time as I am on my 6th 5 gallon bucket of chlorine sticks. Do I add Muriatic acid than ph increaser until I get them both accurate.
Any help on this would be greatly appreciated
thanks
chem geek
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Low pH and High Alkalinity

Postby chem geek » Mon 23 Aug, 2010 19:25

You have two separate problems. The very high TA, assuming you are measuring it correctly, can lead to calcium carbonate scaling of pool surfaces. That's why the pool store is concerned. A high TA can also lead to the pH rising which increased the possibility of scaling as well.

The other problem is algae which most likely is coming from your continued use of chlorine sticks which are probably Trichlor. For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm. So your CYA level may be very high and this makes even high chlorine levels ineffective if the CYA is very high. If the FC drops below 7.5% of the CYA level, the risk for algae grows.

First of all, you need a good test kit so you can make sure your readings are correct. The best to get is the Taylor K-2006 or the TF-100 with the latter kit having more volume of reagents so is comparably priced per test (you can read about the difference in these kits here. To learn how to maintain your pool, I suggest you read the Pool School. You need to test your CYA level and probably need to do a partial drain/refill to lower that level and then shock your pool with high levels of chlorine -- higher than what your current test kit will probably be able to measure (which is why you need a good test kit -- to accurately test multiple water parameters including chlorine using a FAS-DPD chlorine test kit).
Allen G Myerson

Low pH and High Alkalinity

Postby Allen G Myerson » Tue 24 Aug, 2010 07:56

The TA test usually goes from green to red, not blue to clear. High chlorine levels will change the indicator reaction from green/red to blue/yellow. To prevent this interference, add an extra drop of thiosulfate prior to testing.

Use of sulfuric acid (Dry pH down) to lower pH can also cause interference with the TA test.
http://www.taylortechnologies.com/produ ... KitID=2230

Much of your TA could be cyanuric acid. TA from cyanuric acid won't cause pH rise or contribute to the Saturation Index.

Six 35-pound buckets of trichlor would raise your cyanuric acid by 400 ppm (assuming no dilution). 400 ppm of cyanuric acid would contribute about 133 ppm to your TA.

Is your pool vinyl, concrete or fiberglass?
What is your calcium level?

You're probably going to need to replace most of your water.
allen G Myerson

Low pH and High Alkalinity

Postby allen G Myerson » Tue 24 Aug, 2010 08:15

Also, the tabs are very acidic. Therefore, unless you've been adding a lot of baking soda, or sodium carbonate, it's unlikely that your TA would be that high. How much pH increaser or Alkalinity increaser have you been using?

Since your cyanuric acid will probably be off the charts, you will need to dilute the sample using about 4 parts distilled water and 1 part pool water to get an idea of where the actual level is. Multiply the result by 5.
Guest

Low pH and High Alkalinity

Postby Guest » Wed 25 Aug, 2010 16:37

I have a vinyl pool

I have added 1 gallon o fmuriatic acid and now my TA is 440ppm

The tes kit I use is a blue kit with 5 test reagants
I guess I should get a better test kit like the ones you have listed.

I turned down my chlorinator to 3- I had it set almost 6.
Now I am afraid my chlorine will not be as high. How should I maintain my chlorine level-- shock more often or add chlorine granuals.

My weekly routine mainteance is-
2- 2lb easy shock and swim
4 cups pool perfect + phosphate free
7oz algaecide backup

is this a good schedule- should I do more or less

thank you for your help
Allen G Myerson

Low pH and High Alkalinity

Postby Allen G Myerson » Wed 25 Aug, 2010 21:05

Your schedule is not good, at all.

The first thing you need to do is find out what your Cyanuric acid level is.

The trichlor tabs contain a lot of cyanuric acid. The "Easy Shock and Swim" contains Sodium dichloro-s-triazinetrione, which also contains a lot cyanuric acid.

You don't need the "Pool Perfect + Phosphate Free" or the algaecide backup.

Why are you adding muriatic acid? What is your pH?

Report back what your cyanuric acid level is and I will be better able to advise you. Your level is probably over 500 ppm, which will make your chlorine effectively worthless.

I need to know your pH, calcium and cyanuric acid levels.
Guest

Low pH and High Alkalinity

Postby Guest » Thu 26 Aug, 2010 11:33

My ph is about 7.2 and my TA is 400ppm

Where do I get a test kit that tests for calcium and cyanuric acid

this schedule was recommended by the company that put my pool in

I will try to find this test kit and get you the results
thanks for the quick response
Allen G Myerson

Low pH and High Alkalinity

Postby Allen G Myerson » Thu 26 Aug, 2010 14:30

With a pH of 7.2, you do not want to add any acid.

You can go to the pool store to get your water tested. You should also be able to order a good test kit, such as the Taylor K-2006.

Here is the K-2006 rebranded by Leslies.

Where do you live?
Guest

Low pH and High Alkalinity

Postby Guest » Fri 27 Aug, 2010 19:42

hi Allen,
I bought some test strips so I could get some resluts. they are reading pretty much the same as the test kit I already have however this one has a few more tests

total hardness-250ppm
total chlorine-5ppm
total bromine-10ppm
free chlorine-2ppm
ph-8.4
ta-360ppm
CA-300ppm

why do you suggest I have a bad schedule. I should add pool perfect or algae backup every week?
please let me know where I should go from here. I know the summer is almost over but I would like to get on top of this and prepare for next year
thank you
Dan
Allen G Myerson

Low pH and High Alkalinity

Postby Allen G Myerson » Fri 27 Aug, 2010 20:50

How did your Total Alkalinity get so high? Have you added any sodium carbonate or sodium bicarbonate?

What are the levels of Total Alkalinity and Calcium Hardness in your fill water?

Is your fill water from the city, or is it well water?

I need to know the "Calcium Hardness" in your pool and in your fill water, not "Total Hardness".

You need a more accurate Cyanuric Acid test than you can get from test strips. Make two samples of your pool water. Make the first one with 4 parts of distilled water and 1 part of pool water. Make the second sample with 9 parts distilled water and 1 part pool water, and have them tested at the pool store. Multiply the first result by 5, and the second result by 10. The results should be reasonably close.

Your schedule is bad because you are adding more and more cyanuric acid when the level is already way too high. You need to stop using chlorine sources that contain cyanuric acid.

You need to begin to use liquid chlorine (12 % sodium hypochlorite) or regular, unscented 6 % bleach (6 % sodium hypochlorite) as your primary source of chlorine. Keep your Free Chlorine at 15 ppm until you get your cyanuric acid down. You need to keep a free chlorine level of at least 5 % of your cyanuric acid level to keep algae away.

I see that your pH has gone from 7.2 to 8.4. That is probably due to test error, but it could also be due to the high Total Alkalinity. High chlorine levels can interfere with the pH test. With you Total Alkalinity being so high, it's important to keep your pH lower to avoid Calcium Carbonate scaling. Keep adding acid to keep your pH at 7.2 until your Total Alkalinity comes down.

Test strips are really not very accurate or reliable. You need to get a good test kit.

You need to get your cyanuric acid to below 90 ppm. To do this you are going to have to drain off part of your water and refill. Don't drain below your ground water level or to lower than 1 foot in the shallow end, or your liner could float, or lose its set. You will have to do this a few times to get your cyanuric acid to less than 90 ppm.

You can ignore the Bromine readings on the test strips unless you have ever added bromine or bromide.

You are reporting a total chlorine of 5 ppm and a free chlorine of 2 ppm; is that accurate? That means that your combined chlorine is 3 ppm. You need to get an FAS-DPD test kit such as the Taylor K-2006.

The first thing you need to do is add acid to get your pH to 7.2. Add 1 gallon and allow 1 hour for the acid to mix and react, and then retest. If it is still high, add some more acid, wait another hour, and retest.

Once you get the pH to 7.2, add enough liquid chlorine to bring your Free Chlorine up to 15 ppm. Add 9 gallons of regular, unscented 6.0 % bleach (Clorox or store brand Ultra Bleach). Make sure to get unscented, regular bleach and make sure that the label says 6 % sodium hypochlorite. Don't get "Splashless" or other special bleach. Or, you can get 12 % liquid chlorine and use half the amount (4.5 gallons).

Forget about Pool Perfect, Phos-Free and Algaecide. You really don't need them.

Also, go back and reread chem geek's post. Always pay close attention to chem geek, he knows more than almost anyone. Click on the link that he gave for "Pool School".
Guest

Low pH and High Alkalinity

Postby Guest » Fri 27 Aug, 2010 21:50

I have well water and I do not add soft water. There is no other way to solve the cyranic acid unless I drain the water? I will have to have water trucked in.

I dont think my pool company has a clue how to maintain a pool unless they are telling me BS to buy chemicals. I went through 6 50 gallon buckets of 3" chlorine sticks becuase I kept the chlorine high to avoid the algae. would have benn nice to tell me before I screwed up my pool

I will order a good kit

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