your ppm is verry low,u need to add a suppliment,like cal mag keep adding and testing until your ppm is over 150 and under 250.play with it. what kind of medium do u use and did u soak it in pre bufferd p.hd water? so this is the combo 24/7 with three probes right? i honestly couldnt tell u y you would be having these problems as soon as u drop the tds side into the rez.when u pull it out does the ph probe instantly change back to its original reading?maybe clean the shit out of the probes and your rez re calibrate every thing just 2 see it it helps. i will head down to the basement 2 marrow and go through my boxes of gear and see if i can find u the exact instructions off the bottle"i dont need it any more" it should be on the bottle whenu buy it,unless botanicare has changed there labels again.ask the guy at the store he should have product catalogs on a counter somewere.