Low TA for the first time

[jrbevis]

Hello all,
This is my first pool so it's also my first time transitioning to fall. In the last few weeks, I've had to do two doses of baking soda to raise my TA. I presume this is due to less evaporation which equals less auto-fill. My city water on average has a TA of 160. So during the summer when I have lots of evaporation I'm adding more city water which is naturally keeping my TA in check.
My question...
Is my hypothesis correct?
Is it normal that as you transition to fall/winter with less evaporation, you'll get lower TA and will have to start adding baking soda?
Thank you
Jeff

 

[mknauss]

How are you testing your TA? Your logs show a TA of 55, which is not a readable result using a proper test kit.

Your use of acid should be very low if you are not adding water. I still have to add some water each day due to evaporation.

I have never added baking soda to our pool water.

 

[mknauss]

With your volume pool, you should never be adding more than 8-12 oz of 31.45% muriatic acid at a time. That will lower your pH by .4 or so.

 

[jrbevis]

How are you testing your TA? Your logs show a TA of 55, which is not a readable result using a proper test kit.

Your use of acid should be very low if you are not adding water. I still have to add some water each day due to evaporation.

I have never added baking soda to our pool water.

I'm using the Taylor test kit. On my last test, the color did not change to full red at 5 drops. It was also noticeable that 6 drops were not required to make the final change to red. Resulting in my reading of 55.

 

[mknauss]

Your TA is 60. No guessing in between.

Your CH is very stable. Are you using softened water for make up water?

 

[jrbevis]

With your volume pool, you should never be adding more than 8-12 oz of 31.45% muriatic acid at a time. That will lower your pH by .4 or so.

Good to know. I was just following what the app told me to do.

 

[mknauss]

The app is a tool. You have to tell it what is best for your pool water chemistry.

 

[jrbevis]

Your TA is 60. No guessing in between.

Your CH is very stable. Are you using softened water for make up water?

I'm using city water that is not softened. Out of the tap, it averages CH of 225.

 

[mknauss]

Then there is no way your CH has remained stable according to your Poolmath logs. I use softened water and thus my CH only rises slowly. But yours should have gone up at least 200 ppm over the summer. There is a testing issue.

I use the same fill water. Colorado River water. The CH is 250 ppm and the TA is 130 ppm.

 

[jrbevis]

The app is a tool. You have to tell it what is best for your pool water chemistry.

Then there is no way your CH has remained stable according to your Poolmath logs. I use softened water and thus my CH only rises slowly. But yours should have gone up at least 200 ppm over the summer. There is a testing issue.

I use the same fill water. Colorado River water. The CH is 250 ppm and the TA is 130 ppm.

I can't explain that all summer long adding 14-16 drops of R-0012 is what it took to achieve full blue.
My fill water as of last week (which wasn't much different than my previous results).
PH 8.3
TA 160
CH 225
FC .5
CC .5

 

[mknauss]

You will know when the CH rises above 500 ppm, the SWCG will start to shed scale.

I would suggest you not lower pH so aggressively. You should never have to add baking soda when using a SWCG for chlorination. If you used Trichlor, you would need to add baking soda as it is so acidic.

 

[proavia]

Add your test kit brand and model number to your signature.

https://www.troublefreepool.com/account/signature

How are you testing your salt level?

Are you using a speedstir (or similar) when testing.
As @mknauss states, there is no way your CH could remoain relatively constant for months - especially in summer - given your fill water CH.