7 day flush seems to be plenty in hydro/Flood & drain. Plan on using a additive like clearex or just plain water? I researched some more about H&G, seems it was created by a guy who left canna. Good stuff indeed, I might have to give it a try in the future, unfortunately closest supplier is 1 hour drive. Best of luck on the remainder of the grow.
Edit: Can you throw up some lights out pics for us? Right after your 12 cycle shoot a few flash shots. Amazing the difference in look.