Seaweed cultivation can serve as an innovative solution to recycle nutrients in effluent from land-based aquaculture systems, and here, the green algae genus Ulva is a promising candidate due to its high phenotypic plasticity, high growth rates, and biochemical composition. The qualities of Ulva have been described worldwide; however little research and development has been conducted in the Nordic countries. This study presents an extensive screening and characterisation of Danish Ulva strains and their performance in a range of temperatures, nutrient regimes and salinities. Ten Danish/German Ulva strains were documented to grow 6-22% day-1 in free floating cultures, of these, several strains of U. compressa, showcased the most stable growth performances (11-32% day-1). Additionally, the optimal temperature for nitrogen uptake in U. compressa was repeatably identified to be around 14-16 °C (30-40 mg L-1 week-1) while tissue concentrations of high value compounds such as ulvan were higher at colder temperatures (150-180 mg g-1). The salinity tolerance of Ulva strongly depended on the nutrient availability, and the growth rate at low salinities decreased 10-fold for U. fenestrata, while salinity (5-25 ppt) did not affect growth of neither U. fenestrata nor U. compressa when nutrient concentrations were high. These results are currently being applied at a land-based salmon production site where the growth of U. compressa is grown in effluent water. Hence, this extensive research and development approach will showcase the potential to integrate Ulva cultivation in a range of aquaculture facilities and hereby diversify the product portfolio, while increasing both profit of the production.