You will be fine, just keep the lights on them and the water Ph to around 5.8. up or down a few points will not make a huge diff unless your strain is supper sensitive. Dont clip any leaves, you will see when they are ready to fall off, then just remove and discard them.
The hydro is alittle tricky at first but you will soon find that it is well worth the effort in quality and yeild, plus they finish faster.
Pay attention to your plants but do not over mother them. They are weeds, they can live thru alot.
That hydroton looks pretty bright, did you wash the pellets off first before using?