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.
duraleigh
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Low pH and High Alkalinity

Postby duraleigh » Mon 30 Aug, 2010 11:01

Ditto what James Watson said above. You would be at risk of damage if you left it over winter.


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Guest

Low pH and High Alkalinity

Postby Guest » Wed 01 Sep, 2010 20:29

I drained the water to about a foot left in the shallow end as I am going to try an dfix the cyranuric acid level. I haeve lots of alage in the pool since the last couple days.

I am having the water trucked in- any advice to get this pool crystal clear again as the new water is being dumped in

I will check all the chemicals tomorrow evening.
Should I dump liquid chlorine in? how many gallons?
James Watson

Low pH and High Alkalinity

Postby James Watson » Wed 01 Sep, 2010 20:56

Get your pH down to about 7.2 and use liquid chlorine to raise the chlorine to about 25 ppm. Maintain 25 ppm until this clears.

You are going to need an FAS-DPD test kit to measure the chlorine at these levels.

If you get a chance, please post a full set of new readings.
James Watson

Low pH and High Alkalinity

Postby James Watson » Wed 01 Sep, 2010 21:00

You can use the pool calculator to calculate how much regular, unscented 6 % bleach or liquid chlorine to add to increase your FC level.
Jimbo

Low pH and High Alkalinity

Postby Jimbo » Sun 05 Sep, 2010 18:30

If you use Tri Chlor tablets and tri chlor shock and have a strong residual at time of testing it could give you a false PH reading so let the chlorine levels fall and retest. Have it tested at the pool store too as the cheaper home test kit solutions are not as accurate. Try using liquid chlorine to shock and tabs to maintain proper chlorine levels though you will need to use acid but this seems to keep total alkalinity more in line over the long run.
James Watson

Low pH and High Alkalinity

Postby James Watson » Sun 05 Sep, 2010 22:46

Jimbo wrote:Try using liquid chlorine to shock and tabs to maintain proper chlorine levels though you will need to use acid but this seems to keep total alkalinity more in line over the long run.

The poster was using tabs. That is what caused their cyanuric acid to go too high in the first place. Tabs would be a bad choice. Also, tabs are acidic, and require the use of pH raising products, not acid.
duraleigh
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Joined: Sat 07 Aug, 2010 23:26
My Pool: 24X52 DIY Concrete and liner
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Low pH and High Alkalinity

Postby duraleigh » Tue 07 Sep, 2010 07:37

Not to glom on but James Watson has it right. Do NOT use any more tabs!!
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california
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My Pool: inground kinda square with attached jaccuzzi
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DE filter
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Low pH and High Alkalinity

Postby california » Fri 01 Oct, 2010 19:04

Sounds like I too have been using too much tabs. I went away this summer, left the wife in charge of the pool. I told her to just use the tabs. Algea got outta control so I told her to use more tabs. Cleaned the DE filter when I returned, SUPER SHocked and it cleared up. Couple of weeks later the algea crept back then exploded. Over the last couple of days I have put in 4 gal of liquid Cl, 2.5 lbs of shock 30 oz of algecide. I cleaned the DE filter again, still lots of algea in suspension. I'm really suprised all the CL is used up. Seems like I have added plenty.

I hadn't been checking the ph so
I did that today and found the following:
Total Cl .5
Free Cl 0
pH 6.8
Total Alkalinity 240
Cyanuric Acid 150/300

35,000 gallon pool

I just added 2 gallons Cl. Free Cl has moved to 3 same with the total Cl.

Should I dump another couple of gallons of Cl? The pool looks like lime aid.

How should I balance the alkalinity with the low ph?
chem geek
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Low pH and High Alkalinity

Postby chem geek » Fri 01 Oct, 2010 21:32

I wouldn't worry about the TA if the pH isn't rising too fast. You're going to need to do a significant partial drain/refill to lower the CYA anyway and that will likely lower the TA depending on the TA in your fill water. I suggest you read Defeating Algae , but note that it takes a lot less chlorine for shocking the pool if your CYA is lower and you're going to eventually need to lower it anyway so might as well do that now.

The following are chemical facts that should be disclosed:

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm.

So even with a low 1 ppm FC per day chlorine usage, using Trichlor as the only source of chlorine would raise the CYA by over 100 ppm in just 6 months if there were no water dilution.
california
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Posts: 7
Joined: Fri 01 Oct, 2010 16:31
My Pool: inground kinda square with attached jaccuzzi
21000 gal built in the 1960's
DE filter
Location: So Cal

Low pH and High Alkalinity

Postby california » Fri 01 Oct, 2010 21:52

chem geek wrote:...You're going to need to do a significant partial drain/refill to lower the CYA anyway and that will likely lower the TA depending on the TA in your fill water.
The following are chemical facts that should be disclosed:

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.
For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.
For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm.

So even with a low 1 ppm FC per day chlorine usage, using Trichlor as the only source of chlorine would raise the CYA by over 100 ppm in just 6 months if there were no water dilution.


Yeah, that's gonna be some trick. I don't have a backwash on this pool so I don't know how I'm gonna dump the water. Maybe run the water out the filter with the top of the DE filter removed. then it can hit the deck drains and hopefully make it to the gutter. I haven't done a drain down in the 4 1/2 yars I've had this pool so maybe it is time. I added another gallon of liquid Cl since my last post. Started the sprinkler pool feature.

Yes I belive I have been schooled quite well today on the conditioner build up. Thanks its great info and finally I understand. :thumbup:

I am a little curious about the aeration and how that affects the alkalinity.
anyone care to explain or link me to an explanation?

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