Any thoughts why my pH is running low?

[Harry_Y]

I have a well established 180 gallon tank and frag system
all tied together with about 250 gallons of water in it and
for the last couple of weeks my pH is running low.

It normally is around 8.2-8.3 as a high during the day.
I just checked in and it is below 8 in the middle of the day.

At first I though maybe it is not evaporating as much so
the KW top off is not keeping up but the evaporation is
about the same as it has been (abt 3 gal daily).

We have had the windows open a lot more but that is quite
a difference and I thought it went the other way around.

The Things I have done different (did these both 2 weeks ago)

1. Add a Large Rock from a tank that was taken down
(though the rock was still damp)

2. Added some Extra (1tablespoon) Lime to my new saltwater
mixing barrel (1 Tablespoon extra into 25 gallons)

I did recalibrate my pH probe to ensure it was reading correctly

Any Thoughts?

Thank you

PS: I'm at work now but, plan to do a full levels check tonight


.

[briankmarsh1980]

salt maybe.... the buffers/additives in salt can settle try mixing your salt then do a WC? gas exchange?

[Harry_Y]

salt maybe.... the buffers/additives in salt can settle try mixing your salt then do a WC? gas exchange?

I may go get a new bucket and make up the next water change with that.

Gas exchange should be good as all tanks are open top
(Why I have so much evaporation)