Theiaanswered grow question 3 years ago What do you mean by flush? You don't need to flush the plant with biobizz all you need to do is in the last week feed just pH corrected water. Your plant will use up whatever is left in the substrate.. Flushing would remove everything from the substrate and I don't think personally you need to do this. I never flushed when I used biobizz. Just phed water in last week. Good luck 👍🏼