I don’t understand the question
Flush is post flower before harvest
if flushing for correction , flush with water, ph 5.5-6.
Runoff 3-4x the volume of the pot size, may have to do this outside or under a large tray.
After water flush , you flush with the nutrient you are going to use at 1/4 strength 2x thr volume of the pot.
Now you would allow the media to dry out and then start back with all your beneficials your macro, micro feed for about 2 cycles
Then you reintroduce your feed 1/4 strength 1x, 2nd feed 1/2 strength, then full as you see progress on plants .
I run 40% humidity to help dry out the media faster to get back into my feed cycle faster. Then once I’m on half strenght I go to 60% at veg, 50 at flower driving down to 40 by harvest