Total Alkalinity

[Mercer]

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]

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

[Another Pool User]

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]

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]

Thanks. Yes it is vinyl. Cheers.

[nana]

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]

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