I feel like I don't need a picture for this one. The clones have basicly fallen over and well.. Some are developing black spots. What to do? :0(
Without a Pic and details I really can't say. I would guess that it could be a phosphorus or potasium deficiency, though i I'm thinking maybe a pest or fungal problem. Get some pics up an I will try to give you a better diagonosis. If you don't have a camera , then are we talking black dots, circles, tips, splotches, trails, be as specific as possible and I will try to help. How old are the clones? are they fully rooted? what are you feeding them? what is your temp and humidity? soil or hydro? what is your medium? what is your PH and EC of Nutes? There are so many factors to deficiency and disease, detail detail detail if you want a good answer.