Dip that dude 4.01 see what it says, then dip it in 6.86. You know what that 250 ml distilled water and powder is supposed to be .  Calibration is key.iwant :6..5-5.5 ph.  Your as only as good as your meter and a good close Calibration I know bubbling my tap water Raises the ph. To around 8 I would think then add generl hydroponics flora trio. Some calcium and magnesium