m missed this earlier. you asked what is flushing. Well Loc Nar, had the end/finish flushing covered, but if you have an environment or toxidity problem...with a waterfarm you just need to empty your rez, and add ph5.8 water. (((soil 6.5.)))

anyway, turn pumps on for an hour or 2. then add fresh batch of nutrients.

However, you are done...so just remember this info for next time. Peace