Another TA question...

[Florida Penguin]

I have re-reviewed the TA issues with SWG pool. I am doing fine with my pool...I usually add about 3-4 cups of Acid about every 4-5 days. My pH usually stays 7.6-8.0 range (that is when I add more acid..when is hits 8.0 or so). It never gets much lower (due to boric acid in pool @ 30-50 ppm).

However, I keep my TA at about 50. I add a few lbs. of bicarb about once a month, and TA stays around 50 or so.

Should I add more bicarb to keep TA at 70? I remember some of info posted a few months back talked about keeping SWG pools closer to 50 to "slow" the pH rise.

However, I now see the recommendations are TA of 70.

Is this just a minor difference, or am I headed for trouble if I keep the TA too low (ie. at 50).

Thanks!

 

[JasonLion]

The normal recommendation for TA with a SWG is between 60 and 80. A number of people have been experimenting with TA around 50, which has been going really well, but there isn't yet enough experience with the lower TA level for us to include it in the normal recommendations.

Because you have borates between 30 and 50, you should be totally fine with TA around 50. Even without the borates, TA around 50 is probably fine, but I can't say that for sure yet.

 

[chem geek]

If the pool is a plaster pool or has tile with exposed grout, then you should use The Pool Calculator to make sure your saturation index isn't too negative. You can increase the Calcium Hardness (CH) or maintain a higher pH target to compensate. Be sure to include the salt level in the calculator. If your CYA level is 60-80 ppm, then a TA level of 50 ppm with 3000 ppm salt and 300 ppm CH would have a saturation index of -0.6 to -0.7 which is too low. Having the CH at 600 ppm and a pH target of 7.8 brings the index to around -0.1 to -0.2. If you have a vinyl pool, then you don't need to worry about this.

 

[Florida Penguin]

Thanks- I forgot about the saturation index issues and leaching the gemcoat off of my pool walls.

My calcium hardness is 400-450. So, after plugging in the numbersin the pool calculator, my satuation index was -0.29. Appears to be too low.

When I plugged in a TA of 70-80, I get a saturation index of -0.01 to 0.08.

No problem at that level. So I will kick up the TA to 70-80.

Thanks again for setting me straight. As always, you guys rock!

 

[Guest]

Thanks- I forgot about the saturation index issues and leaching the gemcoat off of my pool walls.

My calcium hardness is 400-450. So, after plugging in the numbersin the pool calculator, my satuation index was -0.29. Appears to be too low.

When I plugged in a TA of 70-80, I get a saturation index of -0.01 to 0.08.

No problem at that level. So I will kick up the TA to 70-80.

Thanks again for setting me straight. As always, you guys rock!

ACtually a SI between -.3 to + .3 is acceptable but you are near the edge. The good news is that the trend is your pool is for pH to climb so that would make the SI move toward scaling conditions, so you are probably still fine with a SI of -.29