Leave problems

just follow instuctions on the label for cal-mag product. do you use RO? if so, switch back to tap, that could be the source of the Ca def. Some brands expect it to be there and skimp. If your feed has a good Cal component, like cal nitrate, look into other possible causes. P and K tox could cause a cal/mg def, but it'd also look differently elsewhere than what i see in your pictures, but you don't want to dump more Ca if you already have enough. if you have kept track of when you feed and it's been ~500ppm the whole time, i'd guess you need more nutrients.

hold your PH around 6.0. give a bit of N and CAL-MAG. THE STAINS ON ITS LEAVES COULD BE A LACK OF CALCIUM WITH MAGNESIUM. and the light color a lack of nitrogen. happy growing

Thank you for response, PH is always fixed to 6.5 but have never added Calmag before, how much cal mag should I add to one gallon solution ?

Well if the PH is right then Magnesium and Calcium deficiencies - Cal-Mag