Day 1 : understood the reason why weed is not strong. Fungi gnats. Yeah these small mother fuckers. They are the cause apparently. Not the heat, not lights, not magnesium. Yeah. I did some adjustments, cleaned the place, decided what to do with the waters (throw them away). Good thing for me. Doing things slowly and step by step.

Day 2 : I put the old solution containing (4/4/4) in. smell like shit. I try next days to bring outside air in by intervals. To see how this goes with the gnats. ph too high this morning (7.6 ph)

Day 4 : after some modifications (15 minutes interval instead of 10) and fan tilt correction to properly fan the plants, I feel like there's less gnat propagation and the gorilla leaves feel a bit better. the top left plants buds are getting bigger but still no way close to chronic.
Day 5 : conclusion : problem comes definitely from gnats. So I can increase the fertilizers, no problem. light closer.