water to waste with plain pH corrected water when you flush. When water is pouring out the bottom you're there (not flooding like Pakistan, just coming out of the drain holes steadily). At day 1 of week 7 of flowering I planned on stopping all nutrients and watering with plain water as I normally would (water to waste). If you mean for flushing because of nutrient burn and that sort of thing as a repair step mid-grow then use 2-3x the volume of your container for 2 days then return to your normal water/feed schedule when the plants show improvement. Don't over water.