what nutes are you using? what type of water are you using as well (r.o., tap, well, rain water etc). whats your ph? a little more info would help. but if im not mistaken its a calcium deficiency.
Well I'm using tap water with an nutes ppm to around 980. I made the clone about two weeks ago and they rooted around a week and a half ago. Its been a little over a week since I put them in the net potsclone at around week one