Used to be no problem I feel 'back in the day' of starting with all live rock. I've struggled to get meaningful purple/red growth starting with dry rock until over a year in, even after the bottled stuff. All For Reef seemed to increase growth. There was some green stuff that seemed calciforous but not as thick or smooth as the purple stuff that grew in. My dry rock overall is pretty ugly and I'll never do it again except for base rock/rubble.