Total alkilinity

[emac]

My plaster pool (one waterfall) is 3.5 years old. Following TFP I have had very few issues keeping a clear pool and for the most part, the pool is in fact trouble free. I test the water often and it is always in balance. My question is about low TA.

Over time my PH will creep up to 8.0 and I add acid. Usually need to add acid every 10-14 days. The pool builder told me to expect to add acid for a year and then it should level off. It hasnt. My TA will drop into the high 20's to low 30's. On several occasions I have added a lot of baking soda to get the TA up to a good level, and it will slowly drop back down into the low 30's. The pool seems to like this level of TA. CH is a little high in my water around 350 or so. With the low TA, high CH I can easily keep the pool balanced by adjusting PH. I run my pool year round as it has a connected spa.

I guess my question is should I just go with the low TA numbers and keep adding acid or should I go crazy and add a lot of baking soda and try to get the level up. Do some pools just have their own "balance"? My testing chemicals are fresh and this is how the pool has acted for 3 years.

 

[ajw22]

What test kit are you using?

What is the pH and TA of your fill water?

Do you have an autofill?

 

[emac]

We had a lot of rain this year and I am sure it vaires, but the rain tests at PH 6.5. My house has a softener and I will fill with that because my well water has a lot of iron and is pretty hard. The PH of it is 6.8 and TA is 137. No autofill.

I use the ColorQ Pro 7 tester. It is a digital tester.

Do other plaster pools need a lot of acid even after 3 years? I think the waterfall tends to increase the PH.

 

[ajw22]

Waterfalls, spa spillovers and other water features running create aeration which cause the pH to rise and require increased acid demand.

Aeration - Further Reading

www.troublefreepool.com

If you are adding fill water with a pH of 6.8 and TA of 137 that should be pulling your pH down and TA up.

I suspect that your Color-Q is not giving accurate TA results. A digital tester does not make it an accurate test. I suggest you get your hands on a Taylor or TFTestkits titration TA test and see how the results compare.

For more on the ColorQ read Pool Test Kits - LaMotte ColorQ

 

[emac]

Thank you ajw22, that is a good idea and definitely worth a try. I bought the ColorQ prior to finding this site.

 

[Dirk]

I think @Jimrahbe knows this one. It's a little vague in this ol' brain. Isn't it the Q's TA test that is not actually TA and its TA result is not the same TA that we use here from the Taylor TA test? Or am I thinking of something else?

 

[ajw22]

I think @Jimrahbe knows this one. It's a little vague in this ol' brain. Isn't it the Q's TA test that is not actually TA and its TA result is not the same TA that we use here from the Taylor TA test? Or am I thinking of something else?

That is the ColorQ actually measures Total Hardness and not Calcium Hardness, no matter what LaMotte calls it in their paperwork.

 

[Dirk]

OK, thanks Allen: my bad, it was CH, not TA. Gotta remember that better. Back to your regularly scheduled programming...

 

[RMcGirr83]

I have the ColorQ and the TA always reads ~30 less than titration. There is also a new reagent out for the ColorQ as well, no idea why but it >seems< to be just a wee bit more accurate (difference usually ~20 compared to titration).

 

[emac]

Thanks for all the replies. I ordered a TFT test kit, and I will do some testing for comparison, and post the results.

 

[Jimrahbe]

E,

I have the ColorQ and love how easy it is to use... but, I only use it to test the difference between my last test and the current test.. Over time this gives me an idea if the value is going up or down. If I want to know for sure the actual value, I use my TF-100. Whenever I get new reagents for the ColorQ, like Rich, I do a comparison with the FT-100, so I have an idea where I am.

Thanks,

Jim R.

 

[emac]

Jim,
Thanks, I really like the ease of use also. How much difference do you get in the ColorQ and Ft-100? Is it significant? I have found that colorQ CH can go way off as the chemicals age (not expired).

 

[Jimrahbe]

E,

I find that it changes with every batch of new reagents.. Sometimes it is very close and other times not so close.

As noted above, the CH test is really a Total Hardness test and can be very different depending on your local water.

Jim R.

 

[emac]

Thanks Jim. I really like the slide rule that comes with the ColorQ.

ernest