insanely low pH and alkalinity -- chemicals didn't help

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
chem geek
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Postby chem geek » Sat 21 Jul, 2007 12:01

Dichlor adds to CYA so unless your CYA is low, do not use it. For every 1 ppm FC added by Dichlor, you also increase CYA by 0.9 ppm. Use unscented bleach or chlorinating liquid instead to raise FC without raising CYA (or CH -- Cal-Hypo raises CH -- for every 1 ppm FC raised by Cal-Hypo you also raise CH by 0.7 ppm).

Richard


CrazyMan

Postby CrazyMan » Wed 25 Jul, 2007 11:02

Refill is done and things are looking much better.

pH = 7.0 to 7.2
FC = 0
ALK = 100 to 120
CYA = 0 to 10

I'm guessing the best thing to do would be to raise the CYA a little (maybe to 25 or 30), then add some sodium hypochlorite to up the FC to around 5 (and pH a little), then finally adjust the pH to 7.5.

Then wait for the FC to come down and the temperature to go up, clean the pool, and actually go swimming!

Oh, and I think I'll use liquid chlorine instead of the tablets from now on and test the water a little more than once every 2 years...
chem geek
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Postby chem geek » Wed 25 Jul, 2007 12:24

I calculate that for your 21,150 gallon pool (assuming that's right -- you can see my calculations for that in an earlier post above) 10 pounds of Dichlor (dihydrate) would add 31 ppm FC and 29 ppm CYA to your pool so you could use that, not all at once, to add both chlorine and CYA at the same time since Dichlor quickly dissolves. This is much more convenient than separate CYA since that takes a very long time to dissolve (it's less expensive, but with the Dichlor you also get chlorine so the net price isn't that much more). I suggest testing the CYA level after you've added half to two-thirds of the 10 pounds, just to see where things stand.

The Dichlor will be acidic when the chlorine gets used (the initial addition is only slightly acidic, but chlorine usage is much more acidic -- that's why bleach or chlorinating liquid are really pH neutral when chlorine usage is taken into account). The Dichlor and chlorine usage would have the pH drop from around 7.1 to 6.74 so to get the pH up to 7.5 you can add 21.3 pounds (4-1/2 boxes since each is 76 ounces weight) of 20 Mule Team Borax. This will raise the pH without raising the TA too much. Another option, since your TA is already high enough, is to just aerate the water. Even turning up the eyeballs on the returns helps if it breaks the water surface, but using a waterfall, shower, spillover or especially an air compressor/pump with a nozzle or hose with tiny openings to produce tiny bubbles in the deep end works really well. Aeration will cause the pH to rise with no change in TA.

After you've reached your CYA target, then switch to using unscented bleach or chlorinating liquid. You may need to add this every day if your pool is not covered and is exposed to sunlight. If you want to automate the addition of bleach or chlorinating liquid, you can look at getting ezpool dotcomThe Liquidator.

Richard
CrazyMan

Postby CrazyMan » Thu 26 Jul, 2007 11:47

I have bags of Sodium Dichloro-S-Triazinitrone labelled "Quick Dissolving Shock". Is this the Dichlor to which you are referring?
chem geek
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Postby chem geek » Thu 26 Jul, 2007 12:08

Yup. That's Dichlor.
Pool Boy 1400

Not enough alkalinity

Postby Pool Boy 1400 » Sun 29 Jul, 2007 17:10

My problem is similar but with 0 alkalinity. What do I do?
Pool Boy 1400

Not Enough Alkalinity

Postby Pool Boy 1400 » Sun 29 Jul, 2007 21:58

Seriously. My TA test also failed to turn green after putting in the indicator and prior to adding, I think it is, the sulfuric acid. Instead, it turned red immediately after putting in the indicator (this is the Taylor Test Kit). What concerns me is my water has a faint green tint to it, indicating, I assume, algae, although my chlorine level is about 7 or 8, according to the Taylor color chart. Should I shock the pool with liquid chlorine? Also, to raise my pH, I have added soda ash, but when I do the soda ash turns to a brown cloud in the water. Is this from the presumed algae? Whaddaya think? I've never had this problem before and I'm on my fourth summer with a pool.
Guest

Re: Not Enough Alkalinity

Postby Guest » Mon 30 Jul, 2007 06:24

Pool Boy 1400 wrote:Instead, it turned red immediately after putting in the indicator (this is the Taylor Test Kit).


This means the pH is lower then 4.5
Pool Boy 1400

Not Enough Alkalinity

Postby Pool Boy 1400 » Mon 30 Jul, 2007 06:58

Yes, I understand that. But an earlier poster, Chem Geek, I think, said it was an indication that the TA was near 0. Since my water has a greenish tint to it, my plan, started last night about 11 p.m., was to add four gallons of liquid chlorine (my pool has 70,000 gallons of water) to shock it. Then, about 7 a.m. this morning, I added 3 lbs of A & H Baking Soda, to raise the TA. I'm going to add some Soda Ash, too, to help raise the pH, but I wanted to do this somewhat gradually. My concern has been that when I added soda ash yesterday morning, and when I added the baking soda this morning, they both turned to a brownish cloud as they dissolved in the water. Is this something I should be concerned about? What's the significance of that? I've never seen that before. Thanks for any help.
chem geek
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Postby chem geek » Wed 01 Aug, 2007 16:20

You've probably got metals, probably iron, in your water. They may have dissolved from the very low pH. You'll need to get your pH up to stop the problem of dissolving metal, but to get rid of the metal in the water you either have to sequester it with a metal sequestrant or do a partial drain/refill or both. If you read my first posts in this thread, the initial red in the TA test means BOTH your TA is essentially 0 AND your pH is below 4.5 -- both very bad things (especially the low pH). Adding pH Up right away is critically important.

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