A study of the relationship among -DO2, ΔN and ΔC was developed when the production or mineralisation of particulate organic matter do not follow the Redfield ratios. A dinoflagellate red tide and a diatom spring bloom are shown as two cases where these Redfield deviations can be found. We propose a new useful tool for modelling water mass mixing and net community production budgets, which includes a chemical parameter ("NCO" = O2 + RN⋅NO3(1-RCS/RC) + RCS⋅CO2) of general application where "NCO" indicates the involved variables (Nitrate-CO2-Oxygen). RN and RC are the fixed Redfield ratios and RCS is the relationship between oxygen consumed and CO2 assimilated corresponding to storage substances. The RCS value depends on the nature of the storage substances. Generally these substances are carbohydrates and the value of RCS=1.