PH droping while in tray??

[scubajoe26]

Help.. Im having problems with my ph dropping while in the trays. The reservoir is at 5.8 and when I measure in the tray durring watering it reads 3.6 also have yellowing leaves and stunted growth. Doing ebb flow and RO water, 800ppm water temp 75 degrees. Tray just cleaned 2 weeks ago.

Also it would be nice to be able to search the word PH on this board. (it wont let you).

Thanks in advance for any help.