NEWBIE NEED HELP PLEASE!! plants sick and general questions (with pics)

So this is my second grow. Did an outdoor last year and yielded 17 grams. This year I am running 15 bag s eeds they are now 3 weeks old and the tallest one is about 6-7 inches. They are in a rubbermaid 17 gallon tote under a 125 watt cfl with a exhaust and passive intake. I have fed once with some heavy 16 veg-A and veg-B, a half feeding of both. Also they are in solo cups in Happy Frog. Some of my plants have been curling up to the sky ALOT and crisping at the edges. Some are drooping down ALOT like i cant explain how much they droop. Then some look fantastic. I flipped the switch yesterday to 11-13 in order to sex the plants (ripping males) before they go out into their final resting places in 10 gallon pots. (hoping they will get to be a good size) Basically all I was to l know is it ok to sex them like this and switch the timing back to 18-6 to encourage veg once again? I will be topping them once i see a revert to veg if this is possible and hitting them with some super thrive. And also can someone help me with the leaf problems I cant figure out what the crisping problem is. I believe the dropping is over watering and have adjusted watering schedule but may be wrong. I appreciate all feedback.

Stop on the nutes. The damage on the outside of your leaves is nute burn. That can also leave your leaves crispy.

No more nutes your happy frog had plenty of them for at least a month .

By you adding just burned the living day light outta some .

I would go atleast 2-4 weeks with out giving them nutes. Water as needed and they will bounce back. After all it still is a weed.

thanks for the replys. Also is it ok to sex them like that and switch back to a veg light cycle?

Yes. I would put them in a place that has complete darkness for about 48 hours. After that wait, you'll notice some tricomes forming on the top of your plant. If your growing inside then you just switch back to your 20/4 or 18/6 etc. if your a outdoor gardener then just place it out side and the current light cycle will place it back to veg. You can also put your seedlings on the 12/12 for two weeks and they'll sex them selves.