Is this PH problem or something else?

OK, Ebb&flow, few weeks into flowering, PPM 1300, PH...My pen was out of calibration.
I just noticed when calibrating my PH tester, I can not calibrate to 4.01. It just will not adjust down that low. I have had that before and it is always the probe needing to be replaced. But it calibrated fine to 7.01 (two different adjustment screws).
Is this probe/meter still reliable?
I had just adjusted my reservoir to 5.5 prior to checking calibration and checked it again afterward. It turns out I have been adjusting low (4.XX) for awhile. I added backing soda to bring it up to 5.5 after recalibrating on the 7.01 side.
Here are some pics of my plants. Does this look like a PH problem that I expect is? I added a booster of calmag into the tank just in case as I am using RO.

yep that shure is.. your fgoing to have to find out if your high or low and correct from there.. check the runout after you water,that will tell you.
[video=youtube;JY_GMRp7VcQ]http://www.youtube.com/watch?v=JY_GMRp7VcQ[/video]

mygirls said:

yep that shure is.. your fgoing to have to find out if your high or low and correct from there.. check the runout after you water,that will tell you.

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I am in hydro so after learning my tester was out of calibration, I took action to correct my hydro PM.
Since you said it is PH related, I am good with that as that is what I thought and if I do things right, the plants will recover.
My remaining question is if a tester can not be calibrated to 4.01 but is still able to calibrate to 7.01 is it reliable?
It will take a few weeks to get a replacement probe.

then what the hell am i thinking, hahahahaha i am very well medicated. LOL

mygirls said:

then what the hell am i thinking, hahahahaha i am very well medicated. LOL

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To me, that is the perfect state of mind.