Please Help! Very low TA and high PH

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
Max01
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Please Help! Very low TA and high PH

Postby Max01 » Tue 01 Dec, 2009 07:47

Hello,

I know this is a pool site but I have a lot of problems with my spa and can’t find any good advice anywhere else, so I hope you can help me!

Straight out the hose pipe, my PH is about 8.4 and my TA is only 50 ppm.

What I always did the last 3 month: After filling the spa (680 gallons) I instantly reduced the PH from 8,4 to 7,2 with about 25 tablespoons of acid. The next day my water became extremely foamy because of the low TA! (And the PH always tended to drop.) So I decided to increase the TA with sodium bicarbonate and got a strange effect: since then my water always turns white if I turn on the jets -after turning off all jets it turns clear again (in about 40 seconds.) Maybe I put too much sodium bicarbonate into the water at once.

I always got these bad results, so I am going to dump the water again (in the next days). The fresh water will have: PH: 8.4, TA 50 ppm. What should I do to get a correct PH of 7,2-7,4 and a of TA 80-120ppm?

Should I lower the PH at once (and then use sodium bicarbonate to raise the TA)?

If I add sodium bicarbonate into the spa, how much can I add at once? I mean, how much is the PH allowed to rise during that procedure (adding sodium bicarbonate)? When should I stop?

If I dissolve sodium bicarbonate in a glass of water should I mix the water until all sodium bicarbonate dissolves and the water gets clear again?

Is there a way to lower the PH without lowering the TA? (I couldn’t find anyone!)

I hope you can help me!
greetings,
Max

Ps: Oh, I forgot: I am using Bromine which levels are always at 2-4ppm.


chem geek
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Please Help! Very low TA and high PH

Postby chem geek » Tue 01 Dec, 2009 16:20

Max,

You are probably getting foaming because your calcium hardness (CH) may be low and you may be entering the spa with soap leftover in your swimsuit. Having the CH be around 120 ppm or so will help reduce foaming, but don't have the CH too high since you don't want scaling (generally keep it below 150 ppm).

You don't need to have the TA at 80-120 ppm unless you find that your water tends to drop in pH over time. If instead the pH tends to rise, then leave the TA lower, but not below 50 ppm. If you want more pH stability at the lower TA, then consider adding 50 ppm Borates via a product such as ProTeam Gentle Spa .

The only way to lower the pH without lowering the TA is to inject carbon dioxide in the water. If you add regular acid, this lowers both the pH and the TA. But as I said above, you can have a lower TA if your pH isn't dropping over time. So add acid first to lower the pH closer to 7.5. As for increasing TA with less of an increase in pH, pre-dissolve it in cooler water and then slowly add it to the spa with the circulation pump running, but the spa jets turned off (i.e. don't have too much aeration).

Richard
Max01
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Please Help! Very low TA and high PH

Postby Max01 » Tue 01 Dec, 2009 20:32

Hello Richard,

Thank you for your answer! I much appreciate it!

My water tends to drop in pH over time. After the spa is filled with fresh water there is no foam. The foam only comes after lowering the pH (and TA) with acid (within 12-24 hours). (I don’t know the calcium hardness but I will buy a good test kit to measure it.)

Please correct me if I’m wrong: After filling the spa I first add acid to lower the pH to 7.5. Should I lower the pH at once or slowly within some days (a week) to 7.5? If I am lowering the pH over a week I will need to add more acid because the pH tends to rise.
I think after lowering the pH to 7.5 the TA level will be at 0-10 ppm.

Ok, the next step: After lowering the pH I slowly add sodium bicarbonate into the water. The PH level will rise a little bit. At which PH level should I stop adding sodium bicarbonate?

Thank you for your help!

greetings,
Max
chem geek
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Please Help! Very low TA and high PH

Postby chem geek » Wed 02 Dec, 2009 02:01

You can use The Pool Calculator to calculate dosages including the effects of adding chemicals that will tell you how much the TA drops with acid addition. I'd add the appropriate amount of acid in a shorter amount of time. When adding the TA, you add enough to get the TA up. If the pH rises some, that's OK and you can add some more acid after you've got the TA where you want it. If the pH rises too much, then you can add acid earlier, but hopefully that won't happen if you pre-dilute the baking soda and don't have aeration during addition.
AlGMyerson

Please Help! Very low TA and high PH

Postby AlGMyerson » Fri 04 Dec, 2009 00:56

A lot depends on what your calcium level is. I will advise based on an estimated calcium of about 100.

Starting with a pH of 8.4, an alkalinity of 50 ppm and a calcium of 100 ppm, the first thing you need to do for pH and alkalinity is nothing.

Give the water time to get acclimated to its new environment and temperature.

On the first day, add some sodium bromide to establish a bromide reserve of 30 ppm and then add about 5 ppm of chlorine from sodium hypochlorite, lithium hypochlorite or sodium dichlor.

On day two, check the pH and, if necessary, add enough muriatic acid to lower the pH to about 7.6 to 7.9, not lower. If it is too low, add enough baking soda to increase the alkalinity by 10 ppm.

On day three, check the pH. If the pH is too high, add enough acid to lower it to 7,6 to 7.9, not lower.
If it is too low, add enough baking soda to increase the alkalinity by 10 ppm.

The goal is to find the perfect alkalinity where your pH will remain stable. If your pH is constantly dropping, then your alkalinity is too low. If your pH is constantly rising, then your alkalinity is too high. If your pH is consistently where you want it, then your alkalinity is just right.

If you can post your calcium level, that would help a lot.

How are you adding bromine? If you're using tabs, then that will cause pH drop due to the acidity of the tabs.

You should use sodium hypochlorite on a regular basis to oxidize the bromide into bromine. This will reduce your usage of tabs and give you better results.

Adding 50-ppm boron from boric acid will also help stabilize your pH.
Max01
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Please Help! Very low TA and high PH

Postby Max01 » Wed 09 Dec, 2009 13:36

@Richard and AlGMyerson: Thank you for your help I did what you said but strange things happened:

After filling the spa I did nothing so the water got acclimated to its new environment! The next day I added acid to lower the pH to 7.6. The following next days the pH always tended to rise so I added enough acid to lower the pH to 7.6 (every day about one tablespoon of acid.)

Now I have a low TA 0-10 ppm. Today I lowered the pH to 7.44. After that I dissolved 3 tablespoons of sodium bicarbonate and added it to the water. The pH rises from about 7,44 to 7,62 in 40 minutes. (The jets were running but WITHOUT aeration!) What did I do wrong?

In the last days I added about 13 tablespoons of acid, now the water got foamy again. Does the acid lower the calcium hardness too? How does the acid (pH down) affect the calcium hardness? (I still don't know my calcium level but I will post it as soon as my new test kit arrives.)

What's really strange: My alkalinity is low but my pH is still rising about 0,15 every day (on average)! If I don't add acid, the pH rises from 7,60 to 7,75 and to 7,90 within 2 days. Why is the pH constantly rising with a low alkalinity? I did not use the spa since I refilled it. The jets were only running if I have added acid to lower the pH. (this takes about 20 mins a day)

I am using bromine tabs. My level is always around 2-4 ppm.
algola
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Please Help! Very low TA and high PH

Postby algola » Wed 25 Sep, 2013 18:34

Just wondering, have you solved your problem already?

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