I put 3/4 cup in my PhosBan Reactor on my 33g... Don't try that at home kids.
I can't say how well it works yet, but I can say WOW IT'S CLEAN!!!! Hardly any dust at all when compared to RowaPhos and PuraPhos. It is also way heavier as I can throttle my MJ400 up to full flow and there are no little pieces making it out of the reactor. I do have it throttled back so the GFO is VERY gently fluttering on the top though.
I will update in a week when I see how it's doing.