Yes it will work 18/6 although I have usually done it in 24/0 since that what my veg tent is using. It will take a while for anything to happen so dont get upset if nothing happens for a couple weeks. You will see new growth from existing bud sites and then it will take off. BTW those plants will be huge after reveg.can i not reveg on 18/6? i have them under 400w metal halide at the moment should i switch the light cycle to 24?