I did the same with my cpr model then i got a skimz with the pump at the bottom and even that one enlarged the holes to get better flow, always allot of bio film at the bottom!As long as they're all tumbling you should be good. I know with my CPR i had to upgrade the rio pump it comes with to twice as large, which was recommended by fellow reefers. I also drilled the flow holes in the bottom slightly larger to increase flow, but it was clear the CPR model had flaws when the media wasn't tumbling properly or when it was clogging up. If yours keeps tumbling it should be fine. I used to run a Reef Octopus HOB pellet reactor as well and the only time i got white gunky stuff in there was when the output got clogged up from tumbling them too much. I believe the pellets were breaking down too fast in the reactor..