Niche differences between organisms result in differences in how they respond to environmental change. Such differences, collectively termed response diversity, have recently been proposed as a key mechanism driving community stability. That is, when declines of one organism are offset by positive responses of another under environmental change, total community biomass is more stable through time. However, there are still few studies experimentally testing response diversity’s stabilising role. Here, we use floating macrophyte communities composed of four clonal species – Lemna minor, Spirodela polyrhiza, Azolla filiculoides, and Salvinia natans – to test whether the diversity of growth responses to nitrate stress can predict community biomass stability. Using 69 mesocosms with replicates of each combination of species from richness 1 to 4 and three levels of Nitrate enrichment, we conducted a 10-week experiment and assessed macrophyte growth and composition through time based on photographs taken every few days. We separated photographs into 100-by-100 pixel tiles, and manually annotated a subset with the dominant species to build a reliable training and validation set. We used transfer learning to extract features from pre-trained DenseNet and VGG models, and a voting system combining both models reduced misclassification. After further post-processing, computer-classified images produced percentage cover estimates and time series dynamics within a suitable margin of error based on manual validation data. We used the resulting macrophyte composition time series to derive growth rates under different Nitrate concentrations and measure macrophyte responses to nitrate enrichment. We found that response diversity increased temporal stability of total macrophyte cover, but that it did not confer stability more than mean species nitrate response. Overall, our results suggest response diversity can be a stabilizing mechanism in floating macrophyte communities, but that other drivers such as mean environmental response, species asynchrony, or population stability, may be equally important.