@Azton your just the new kid on the block, we have been over that topic so many times that our response is canned, its nothing personal.
I grow in rock wool so I ALWAYS Fertigate to 20% run off to waste every day that I fertigate. When it is time to change my reservoir I dilute the strength of the PPM by 50% and I FLUSH the rock wool cubes with 100% of the volume they hold over the course of 8 fertigations in the day. This flushes out any residual nutrients that may be building up out of balance but does not harm the biome. I start the next day's fertigations with fresh in balance nutrients.
Plants do not exuded nutrients once absorbed, they do however exude sugars and hormones to trigger microbes to make the nutrients they most want. So they cannot be flushed once overfed or out of balance.
You can do this kind of flush in coco. It is often used to correct an overfed or out of balance pot If done slowly over a day it does not harm the biome.
You should not do this kind of flush in peat based soil or compost based soil. Flushing peat or soil is usually the final nail in the coffin of an already dying plant. Some of them do manage to fall over the finish line but it ain't pretty.
