Are the clones in rockwool and surrounded by hydroton or are the clones just sitting in the hydroton? Drooping is usually caused by under/over watering. You are probably doing one of those two or - what are your temps at? Is the space ventilated? Could be too hot. A picture says 1000 words - post one and it will be easier for someone here to help! Also - please post how much water and fertilizer you are using - clones are sensitive at the beginning. Post as much info as possible ASAP - hydro is easy to fuck up quickly.