Never had this happen before - pH seems to be dropping?

JimMarshall

Gold Supporter
TFP Guide
Jun 5, 2017
804
Oil City PA
Without any intervention from me? Has gone from being in the high 7s to the low 7s (most recently 7.3) without me adding any acid other than CYA (which affects it but it is negligible). My TA is normally high with the fill water here, and as such my pH always drifts UP and I must add MA to drop several times a year.

Also, my pool water tastes icky. I know that its not supposed to be drank, but its inevitable to get some in your mouth.

Latest numbers
FC 6
CC .5
pH7.3
TA 80
CH 300
CYA 50

We've been getting A LOT of rain here... Is it possible that the rain is just very low pH compared to "normal"?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
21,937
Laughlin, NV
The only way pH lowers in pool water is from a chemical addition or the addition of acidic water.
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
32,555
Sebring, Florida
That is really puzzling. As marty posts above, pH doesn't go lower unless you add some low-pH chems or acidic water and rainfall can not account for that swing.

If you ever figure it out, patent it quickly because a lot of folks would use it!!
 
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JamesW

TFP Expert
Mar 2, 2011
16,005
Is the TA also going down?

How many inches of rain have you received?

Are you getting the water sample from the top of the water where the concentration of rainwater might be higher than the rest of the pool?
 

JimMarshall

Gold Supporter
TFP Guide
Jun 5, 2017
804
Oil City PA
So your next experiment will be to capture some rain water and test its pH.
Hopefully I'll be able to do that today.

Is the TA also going down?

Actually it's been going up, but I had older testing reagents that I just replaced

How many inches of rain have you received?

Since the pool opened? About 30

Are you getting the water sample from the top of the water where the concentration of rainwater might be higher than the rest of the pool?

I am, hadn't considered that.
 

JamesW

TFP Expert
Mar 2, 2011
16,005
Most likely it's just the rain. Monitor closely for a few days to confirm.

Bring the fc up to about 20 and do an OCLT.
 

JimMarshall

Gold Supporter
TFP Guide
Jun 5, 2017
804
Oil City PA
This morning I was at 19.5 and 1.5 CC - water crystal clear. I might have screwed up and let the chlorine drop for a couple days (life gets in the way sometimes).... but at least whatever it was that I was about to have an outbreak of..... I seem to have been able to "head it off at the pass"