TA and PH question

[DanWC]

So I admittedly do not check my TA all that often because at the start of the season every time I tested it, it always stayed around the same which was 90. I didn’t have much issues with my PH so I opted to just not worry about it and let it stay at 90.

Today I am running my tests and wanted to check TA as it had been a while since I had. My PH still was not giving me any trouble and basically stayed around 7.8, occasionally drifting up to 8, so I’d add acid to bring it back down. Not much acid added recently.

When I ran my PH test it was somewhere around 7.4 which really surprised me as just a few days ago it was 7.8. So I figured my TA must be off if my PH swung down. Sure enough my TA was 40.

I happened to look at the PH reading as I hadn’t dumped it out yet, and it had changed while I was testing the TA and was now reading 7.8. Can anyone tell me if this is normal for PH to change if it sits for a couple minutes?

I decided to recheck both TA and PH. TA again came back at 40. But PH immediately showed 7.8 on this test instead of 7.4.

Guess I will head off to store tomorrow for some baking soda to get the TA up.

But can anyone tell me why my TA dropped? I hadn’t really been adding much acid and every single time I tested before it was always at 90.

Thanks for any help!

 

[PoolStored]

Can anyone tell me if this is normal for PH to change if it sits for a couple minutes?

Yes.

But can anyone tell me why my TA dropped? I hadn’t really been adding much acid and every single time I tested before it was always at 90.

Water Testing Errors - Further Reading

www.troublefreepool.com

Clean your vials with rubbing alcohol and dry
Get fresh reagents
Use a speed stir
Hold reagents vertical
Slowly squeeze, allowing drops to form and drop under their own weight
Continue drops until the color does not change again, then subtract the last drop
Wipe the tip of the R-009 with wet towel/coffee filter/paper towel between drops

Your TA was 90 on May 8.
You added 8, 12, 12, 30, 30, 35oz since then, or 127 oz. This would lower your TA by about 30, or a resulting TA of 60. Testing error is likely the difference.

 

[pjt]

Guess I will head off to store tomorrow for some baking soda to get the TA up.

Hold off on that. For the TA test, are you continuing to add drops until there is no additional color change? (For me, it typically takes another 2-3 drops after the initial color change.) TA of 50 or above is perfectly fine. Be judicious with your MA additions as your TA approaches 50. Under normal circumstances, a non-trichlor pool should never need baking soda.

What's the TA of your fill water?

 

[DanWC]

Hold off on that. For the TA test, are you continuing to add drops until there is no additional color change? (For me, it typically takes another 2-3 drops after the initial color change.) TA of 50 or above is perfectly fine. Be judicious with your MA additions as your TA approaches 50. Under normal circumstances, a non-trichlor pool should never need baking soda.

What's the TA of your fill water?

Thanks for the replies.

I will have to test fill water as I’m not sure. But haven’t been adding much water recently and never had TA change after adding water before.

I just find it odd that my TA dropped all the way to 40. Like I said, it earlier in season no matter how much acid I was adding, TA stayed around 90. I certainly do not think I’ve added enough acid this year to drop TA 50 points.

And also the PH reading 7.4 one test and 7.8 the next. Seems weird but maybe that was user error.

I will have to test TA again make sure I didn’t not stop the test short.