You may want to try switching from CaCl2 to CaSO4.

I used to dose CaCl2 in my 180G. I used slightly more than you are dosing, but not by much. I constantly had problems with certain plants but not with others. Switching to CaSO4 and dosing less GH overall, as suggested by Tom, solved all the problems.

I don't know if there is any direct proof of CaCl2 being bad for plants, especially at low levels, but in my experience, as well as in some other posts I have read elsewhere, the Cl may have a negative effect, andmay as well be ruled out as an issue since it provides no benefit anyway.