Deficiency or over overfertilization? HELP!

No spider mites, thank god! I don't believe that it's overwatering either – I have 4cm of hydrotons in the bottom of the 20l fabric pots and I only water when dry (every other to third day). I'll order a bottle of Bio-Heaven and see if that helps! I read that Biobizz All-Mix should have all necessary nuts for the first 6 weeks or so – but then again they do advocate for 1ml/l Bio-Grow from week 2 in their own schedule. Regarding the lights I'm following Mars Hydros recommendations of 18-24" (46 - 61 cm) and 75% light intensity (have a knob for that). It could be wort mentioning that we have alkaline hard water here (around 8.6-9.5 PH and 120-180 PPM out of the tap) – so I lower it with Biobizz PH-

to be frank - once some leaves looked like that. I checked - and they had spider mites. plz check! :) Otherwise I would go with overwatering - is your watering ok? I also recommend to try stress-reducing additions, algamix and bioheaven. Helps a lot for me. I use Biobizz with Lightmix and always go strict to the scheme (and add more grow-nutes). Overfertilization in VEG always came with dark green leaves first - which you don´t have. But overfertilization mostly comes more later or in early flowering. Greets and peace!