One other thing I just noticed is you keep mentioning filtered water. Some filters actually add sodium to the water, plants do not like extra sodium.
If this is the case it could explain the yellowing of the leaves, but not the rising ph. I do believe the ph is from the hydroton.
Maybe try using just regular tap water, give it a week and see what happens.

That's just my :twocents:

Best of luck to ya. :hippy:
tikiroom Reviewed by tikiroom on . Need help with rising Ph....! I've got a bit of a dilemma...! I now have 12 plants in bloom, 3 sets of 4, spaced out by 1 week. My problem is rising Ph. My water that comes into the grow area goes thru a cylindrical water filter, one you use for water going to a refrigerator. From there it goes to a 50 gallon reservior that is aerated and constantly moving. The water comes in at 7.8-8.0 Ph and 80-180ppm. I'm using GH FloraNova products that after mixing brings that water to 5.8-6.0 Ph and 1200-1400ppm. I run the pump for 15 Rating: 5