Just to keep everyone in the know, I installed my R/O filter....................my pH and TDS beforehand were 7.5/150, and afterwards, it's at 8.0/3.
Not sure how the fugging pH went up (as the main reason I purchased the filter was to throw away my pH down - that's clearly not happening, but such is life).
The meter reads 8.0 but that is not the pH of RO.
RO has no ions and your meter cannot read it.
If you add anything to RO
so you can read it
then it is n ot RO anymore.
I highly recommend that you avoid putting your pH probe into RO water
as it will eventually do permanent damage to your probe.
You should only measure the EC of your RO,
but never try to measure the pH.
The pH of RO is 7
but since there are no free ions
the meter cannot measure it
and you get 6.5 or 8.0
That is why you need to use 7.0 calibration fluid to check your probe,
since 7.0 cal fluid has the free ions necessary to read that pH