I will seed it through the small pumice, I currently run in my reactor and I will dose carbon from the beginning, thenYou need to seed the reactor and add carbon source for a week or two otherwise it will take longer to start bacteria colonization. You can reduce the carbon on 3rd week to a maintenance level to maintain small amount of no3.
How long did it take to get the bacteria colonized enough to process the nitrate? Also, how much flow do you want entering the tower ?
Donovan your system would most likely be a source of bacteria plankton much like the DyMiCo filters are said to do. Although with them, they recommend you not use a protein skimmer to preserve the plankton in the water column for the corals