The specific version of the AQUATOX model to use will depend on your specific research needs and the compatibility of the model with your data and objectives. It is recommended to consult the AQUATOX documentation and resources, or reach out to the model developers or experts in the field for guidance on which version would be most suitable for your study on nutrient simulation in the Karun River in Iran. Regarding the research records worked in the model library, you can utilize available data and records relevant to the Karun River, such as water quality measurements, nutrient levels, and any other relevant parameters. While measuring plankton can provide valuable information on the ecosystem dynamics and nutrient cycling, it may not be necessary if your research focus is primarily on measuring nutrients specifically. However, considering the complex interactions between plankton and nutrient dynamics, it could be beneficial to include plankton measurements in your research to enhance the accuracy and comprehensiveness of the model simulations.