Two ecosystem models, one with dissolved organic matter and the other without, were run to equilibrium in a global ocean box model. Predicted distributions of nitrate and dissolved inorganic carbon were similar between the two runs. Export fluxes to the deep ocean were dominated by sinking particles in both instances, and so showed little sensitivity to the choice of whether or not an explicit representation of DOM is chosen. Significant differences did however occur in predicted primary production and f-ratio, giving rise to alkalinity changes (up to 22 mmol m-3) which could be important when calculating pCO2 and atmospheric exchange of CO2 in studies addressing the global carbon cycle.