Ugorg is right all you're going to get is mixed replies. Most of people's questions can be answered by your own experimentation. Then you'll find out what works best for you.
I use Bio-bizz too , i used to flush two weeks before harvesting, but i now flush two/three days before harvest.. i flush til clear water runs off, u will still have salts built up or sum bloom feed run-off.. hope this helps.
Gaz
Learn why people flush, what it actually does, and how it could benefit you then make that determination yoursefl. It has nothing to do with brand or type of nutes..
I would recommend only flushing if you have high levels of N near your estimated chop date as this will hinder the cure