flushing?

If im using all organic nutes, in coco coir, do I need to flush it out. When or

how often. Ive seen products made just for flushing out soil, do you guys use these, or just plain water?

Well, you obviously should if you get nute burn or the soil gets "salty." Begin flushing 7 days before harvest. I'm not sure how well final flush works, but supposedly you can use it 3 days before harvest.