my pH has been wrong... do I need to flush?

Ok guys I just realized my Hannah pH pen has been giving me the wrong pH, and so I have been feeding my plant with much too acidic solution for god knows how long.

I realized this because I tested my pH pen into a gallon of distilled water I just purchased, and the pen read 4.5 pH... If I understand correctly, distilled water is 7.0 pH. Should I calibrate my pen according to this? I ordered some 7.01 buffer solution but it's going to take a while to get here..

Also what should I do with my plants? Do I need to flush them ? Or just start feeding them with properly adjusted pH?

fuuuck this could be bad, one of my plants is lookin pretty ugly. 15 days until harvest too...

Hey, I found out the long way that all bottled water / distilled water / R-O water is going to be different PH levels depending on the manufacturer and even then it can differ a little. I bought R/O water from wal-mart at it was PH 8.5, my tap water is PH 8.2, Some distilled I tried was 5...Its all over the board.

best thing to do is buy the calibration liquid for your meter which you already did I have a meter with a glass ball thing as a sensor and I usually have to moisten it a few minutes prior to use for best results.

After using both R/o and distilled water, i think im going to just buy a Brita filter and use my tap water + let it air out for 24 hours before use. (possible mix 1/2 tap + 1/2 r/o)

Thx, gonna bump once for a second opinion

Definitely agree with the poster above, if you're going to be relying on that meter, you need the calibration solutions (both of them). I've had distilled range anywhere from 6-8, and my RO water is about the same, I have to check it weekly.

How bad is it for the plant that the solution i have been feeding has improper pH? what am i looking at here? one of my plants seem fine, but the other has turned really pale and droopy.

If I understand............. Until the calibration solution gets there, you're not really sure that your meter is off. ?
Until your Cal Solution gets there, you could go to a fish/pet store and buy a test kit and test your nute batch.