Yepp, drain to waste with coco means top-feeding and best would be ~20-30ml run off per plant per feeding.
And what @kushedy said is true. 20cm is not enough, 40 from tops and 60cm from canopy is far better and it's much easier to keep the plants happy.
Well, actually to this sick plant, light is 30cm from tops. Anyway... Thank you all for help, I know what to do next time, I hope next grow will be better than this one.
Next grow is always better than previous!
