O-2 depleted water now occupies the center section of your chamber. The bio media provides the area for the denitrifying bacteria to gain a foothold and begin to florish. The amount of nitrate concentrations will ultimately determine the size of this colony once fully established. You aren’t going to see results for almost 2 full months so sit back and monitor only the drip rates as your denitrator matures.
The coils have nothing to do with the actual conversion of nitrate into nitrogen. All they do is to provide surface area for aerobic bacteria to strip the water of all available oxygen as it works it’s way into the center section.
I think that this is where a lot of the confusion over the project enters the picture. The slow flow rates allow the water to “stagnate” to the degree that dwell time is provided for the conversion process. Too fast a flow and complete breakdown cannot occur, resulting in nitrite production. Too slow a flow rate and the possibility that hydrogen sulfides might be produced. You’ll know when this happens as the odor of the water leaving the reactor will smell like rotten eggs. This is a bad thing and the effluent should NOT be allowed to re-enter the main water system! Simply increase the flow/drip rate and discard the effluent until the odor diminishes. Top off your sump/aquarium accordingly with fresh water to compensate for this loss in water volume.
Thanks for your interest and the best of luck with your project!