First time BIG BANG AUTO

Ok so as ya can see to all those interested in basic soil I wouldn’t recommend it over coco. The 2 in coco are double the size of the regular soil tester. The coco two seem to have stopped in height growth as I imagine the are now focusing on root growth. I’ve also decided to give the soil one away as 3 might be a tight squeeze in my set up so to benefit the others in longer term thinking I’ve this decision. I’ve only watered very lightly twice this week with bottled water at room temp. I have also found one of the two have slightly drooping leaves oppose to the other one as you can see. The images are taken with flash and without to show better the soil colour to possibly have some advice if I’m over/under feeding. Also if anyone could recommend a nute selection to buy that isn’t too costly or difficult (as I’m a beginner) to start feeding them in 1-2 weeks. ANY IMPUT WOULD ALWAYS BE WELCOMED AND APPRECIATED. May the bud be with you all