Total Alkalinity

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

Total Alkalinity

Postby Mercer » Sat 19 Jul, 2008 08:19

I have a 16'x48" vinyl pool with a salt water system . It is working great but my total alkalinity is low any suggestion.


Guest

Postby Guest » Wed 30 Jul, 2008 03:45

How low? Normally with a salt water chlorine generator pH and TA rise.
Another Pool User

Low Alkalinity

Postby Another Pool User » Wed 06 Aug, 2008 18:51

I have a Salt water system, 16x48 ultra frame pool. Low Alkalinity problems right now. I would say the level is 70 right now.

Could this be a result of using table salt by mistake during pool start-up?
Should I take action to corret the problem?

No results like below occurring right now though:

• etching of the plaster, marbelite, marcite or tile grouting;
• corrosion of metal parts (pool heater, steps, scoop pole, . . .);
• staining of the pool's surfaces;
• green water;
• burning eyes and itchy skin;
• pH bounce (rapid fluctuations in pH).

And the pool water is not yellow. :)

Thanks.
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Re: Low Alkalinity

Postby chem geek » Wed 06 Aug, 2008 20:05

With an SWG pool, the pH will typically rise (but the TA will not unless there is evaporation and the fill water has TA). You are actually better off with a somewhat lower TA as that will reduce the rate of pH rise, but you are correct that you need to compensate for that with a higher target pH (say, 7.7) and/or a higher Calcium Hardness (CH) level, assuming your pool is a plaster pool (not vinyl). You can use The Pool Calculator to calculate the saturation index and be sure to include the salt amount and temperature since that affects the calculation. It's OK for the index to be slightly negative -- say, -0.2, since that helps reduce calcium carbonate buildup in the SWG (though most SWG systems reverse polarity to minimize this effect). Again, if your pool is vinyl, you don't need to worry as much about a negative saturation index. I'm not sure what an "ultra frame" pool is made of.

Richard
Guest

Total Alkalinity

Postby Guest » Sun 10 Aug, 2008 05:17

Thanks. Yes it is vinyl. Cheers.
nana

Reducing Alkalinity and also got low pH

Postby nana » Tue 10 Mar, 2009 13:04

My pool test kit told me TA was above 200ppm. I used 4 bottles of 7 LB hth pH minus to lowing total alkanility. However, now TA is 140ppm, pH is below 6.8. What should I do next/ To rising pH or still lowing TA. waiting for your advises.
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

Reducing Alkalinity and also got low pH

Postby chem geek » Tue 10 Mar, 2009 21:37

nana wrote:My pool test kit told me TA was above 200ppm. I used 4 bottles of 7 LB hth pH minus to lowing total alkanility. However, now TA is 140ppm, pH is below 6.8. What should I do next/ To rising pH or still lowing TA. waiting for your advises.

Aerate the water. That will raise the pH with no change in TA. According to my calculations, the drop in TA you saw from the acid you added implies a pool size of around 21,500 gallons (if the TA were 220 initially, then the pool size is around 16,300 gallons). Is that about right? You added too much acid and your pH actually dropped to around 6.6 (6.8 is probably the lowest reading in your pH test). Nevertheless, if you aerate the water, the pH will rise.

Aeration can be done by pointing the returns up with the pump running on high. You can also turn on any water features such as fountains, waterfalls, spillovers, etc.

Richard

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