Sustained high range TA and occasionally low PH.

[Patriotryan]

My pool has been trouble free and crystal clear all season. I have had a high range TA for about a month 100-120. My PH will slowly drop over the time span of a week 7.8 drop to 7.4. This is also after adding a hour or so of water 2 times over the week for evaporation and use. I have had good chemistry otherwise.

I am curious if the TA hovering around 100-120 should be addressed or is this ok. Additionally when I raise PH I am wondering what others do to raise PH only. I have used PH up from the pool store but this will still raise the TA a little bit too. I am trying to air-ate the water too, but have found it a VERY slow process. I attached recent test results.

TIA!
Regards

 

[mknauss]

Welcome to the forum.
You say the pH falls without the addition of acid or acidic chemicals? That is extremely rare. Especially with a TA of 100 as the equilibrium pH with that TA would be in the low 8's.

Your Poolmath shows you using trichlor. That is very acidic. Stop using that and your pH will rise.

 

[Patriotryan]

Hey, thanks for the input. I have not used any acidic additions purposely. I use trichlor 3” tabs in the chemical feeder set to 4.5 on the dial. Are you suggesting to turn off the chemical feeder when I need to raise PH or stop use all together? I typically only need to make small chlorine additions with 65% cal-hypo after pool heavy use. Thank you for your advice and input

Welcome to the forum

You say the pH falls without the addition of acid or acidic chemicals? That is extremely rare. Especially with a TA of 100 as the equilibrium pH with that TA would be in the low 8's.

Your Poolmath shows you using trichlor. That is very acidic. Stop using that and your pH will rise.

 

[mknauss]

Your use of trichlor is what is dropping your pH. Typically constant trichlor use is not sustainable as the CYA levels rise and the FC level cannot be kept high enough to maintain the FC as per the FC/CYA Levels

I am surprised your TA stays at that level when using trichlor. Normally the pH and TA both lower and most owners that use trichlor constantly that do not monitor them crash their pH and TA.

Do you cover the pool most of the time?

To raise pH, borax is normally used. Baking soda will raise the TA.

 

[Patriotryan]

Your use of trichlor is what is dropping your pH. Typically constant trichlor use is not sustainable as the CYA levels rise and the FC level cannot be kept high enough to maintain the FC as per the FC/CYA Levels

I am surprised your TA stays at that level when using trichlor. Normally the pH and TA both lower and most owners that use trichlor constantly that do not monitor them crash their pH and TA.

Do you cover the pool most of the time?

To raise pH, borax is normally used. Baking soda will raise the TA.

Your use of trichlor is what is dropping your pH. Typically constant trichlor use is not sustainable as the CYA levels rise and the FC level cannot be kept high enough to maintain the FC as per the FC/CYA Levels

I am surprised your TA stays at that level when using trichlor. Normally the pH and TA both lower and most owners that use trichlor constantly that do not monitor them crash their pH and TA.

Do you cover the pool most of the time?

To raise pH, borax is normally used. Baking soda will raise the TA.

I have been learning a ton this season as it’s my first full season with the new pool. I have been watching CYA as I have been concerned about exactly what you allude to. I have been using approximately 2 trichlor tabs a week in the feeder. I have been told this is a very normal practice in our area with pools equipped with auto feeders. We cover the pool with a solar blanket at night and when not in use during the day.

 

[mknauss]

Covering your pool most of the time will trap the CO2 in the water and your pH will not rise as it normally would with the level of TA you have.

Your CYA of 60 ppm that I see is as high as you want to allow it to go. I would suggest you discontinue the trichlor and use liquid chlorine.

 

[Doormandan]

That explains a lot for me. I always have had high alkalinity (100-130), and use exclusively sodium hypochlorite, but my PH is always low. But I keep the solar cover on 24-7 unless the pool is in use. PH will rise from 7.4 to 7.6 if the pool gets a lot of use in a day, but it will fall again after a couple days. Haven't added acid (other than cyanuric acid and boric acid) in over 4 years.