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.

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?
Ed
 

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.
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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?
savannah
 

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.
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Low pH and High Alkalinity

Postby Pool User » 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
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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).
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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.
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Low pH and High Alkalinity

Postby Pool User » 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
Pool User
 

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.
Allen G Myerson
 

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