Flushing and the x amount of hours before chopping is all horse poo. Feed your plants properly reduce the amount of nutrients at the end of the grow. When I did hydro I’d maybe hit 800-900 ppm and taper off until to 250ppm the last week. No need to starve your plant and have it off eating itself.I have 3 Individual reservoir’s. Iam currently flushing how do i know that my plants are totally flushed enough. And i plan on putting the plants in total darkness for 72 hours towards the end of the flush? Any advice would help.