newbie hydro flush questions

Hey guys, my grow officially started on 2/26/12. I have 3 differant autoflowering strains, northern lights, speed devil#2 and pandora all fem and they are in a flood and drain setup in a dr60 tent with 150hps. I added veg nutes on 3/13/12 and started them off at 1/4 strength. I ran them on veg nutes for about 2-3 weeks never exceding 3/4 strength. They are all in flower mode and have been getting thicker by the hour...lol...I still have a few more weeks to go by the looks of my trichs so my question is when and how long do i flush them for and how long should i have them in the dark before harvest? Any help/info would be greatly appreciated.

Also they have been on flower nutes since 3/27/12 and are at 3/4 strength. I am using canna aqua veg and flower nutes.

It's all a matter of opinion. I'm not a big believer in flushing, I just stop feeding when it gets close. I also don't think darkness accomplishes anything. But I will say that with three strains, they don't all need the same thing but you have no choice but to give them the same thing.

OK ill take that into consideration. I know each strain does require their own attention but so far so good. I wish i had more room but this is what i have to work with. Can you describe exactly how "close" to stop feeding?