Ooh nice, where did you score a blue milli? I need me some blue in my tank.
I found it took at least a week for my newly introduced frags to start displaying good PE. In my case as a new tank I knew it wasn't NO3 or PO4 yet, so I was all worried about not having enough flow and so on. Sort of the opposite of what you were worried about.
The PE was there the first day but then not after that. But then it came back with a vengeance after a week. I should show you a picture of the RP you gave me - it's super furry now.
So I dunno, could it just be that they haven't fully adapted yet but still might given a couple more days?