Another question, this one about pH

[astrong]

Since adding borates our pH was stable at 7.7 now it's down to 7.4 in 1 day.
We have swam in the pool aerated not on purpose but we put the fountain out for the kids to play in but ph has changed from 7.7 to 7.4 this was slow drop over 2 days 7.6 to 7.6 7.7 7.7 7.6 7.6 7.7 7.4 in that order.
What causes ph to drop? I've not seen any factors that can contribute to the drop I've looked.
Test this morning
FC 5.5
pH 7.4
TA 100
CH 60
CYA 40
Borates 50-60 best guess using test strip.
I'm still learning the chemistry of how each thing affects the other.
Is this normal or abnormal

Thx
-Amber



24 round 52 Evolution CLX 13,000 gal, hayward S180T sand filter & 1 hp Power-flo Matrix single spd, TFP method, taylor K-2006 kit

 

[Richard320]

Dropping pH has to be from some external source. The normal tendency is to rise.

If you haven't added liquid acid, how about dichlor or trichlor you added to boost CYA? Or CYA that's still dissolving? It is an acid, after all. Is your refill water lower in pH than the pool? Did you have to make up what was splashed out?

 

[astrong]

Come to think of it it's possible the 5 minutes of rain could have done that. Seriously it rained for 5 min then stopped. Because we have not used any trichlor or dichlor at all ever. And it's been month since adding the cya.
I aerated today it's back up to 7.6.

24 round 52 Evolution CLX 13,000 gal, hayward S180T sand filter & 1 hp Power-flo Matrix single spd, TFP method, taylor K-2006 kit

 

[Scuba_Steve]

Hello there neighbor!

That seems strange because 5 minutes of rain should not have affected anything. Maybe if the pump wasn't running, you took the sample immediately after it rained, and you took the sample from the top of the water. Always go elbow deep!

I know my refill water is 7.8 btw, and I am only a very short distance away.