[JZinCO]

To elaborate on Mark's last sentences, it's important we recognize we would not have N/P issues if we had more available C.
If adding C doesn't lower N, that suggests P is limiting.

Carbon dosing is analogous to using algae with a few exceptions: 1) The rate of bacterial growth is faster than algae, so changes in nutrient availability and pH occur more rapidly, and 2) The bacteria are largely heterotrophic so O2 will drop, and algae increase O2 when fixing carbon. Those differences aside. C, N, and P wind up in the biomass of bacteria. The options for bacteria (or algae) then are 1) release C, N, and P back into the water column, 2) Sequester the C, N and P indefinitely, or 3) Export the nutrients. (1) is counter-productive, (2) is unlikely and undesirable because any O2 consumed by bacteria is unavailable for fishes and corals, (3) is the desirable action and can be done with filters or skimmers.