For systems that harvest kelp before sinking, the mass of kelp grown may be directly measured. For systems that do not harvest kelp before sinking, kelp growth may be estimated with yield models that estimate biomass carbon as a function of species and strain, macro- and micronutrient availability, episodic mortality events like disease & storms, and other environmental factors that affect kelp growth. These models must be calibrated based on observational data, which could be derived from direct sampling and weighing, or from indirect measures from conjoined observational buoys (e.g. with instruments pointed at growing kelp). The mass of kelp grown can be converted to carbon using a default carbon content factor.