Harmful algal blooms (HABs), or the explosive growth of harmful algae, are increasing in severity and frequency in water bodies worldwide due to human activities and climate change. HABs’ ecological dominance, high biomass, and release of toxins disrupt ecosystems and deplete water resources. HABs are influenced by abiotic and biotic factors, including light, temperature, nutrients, and grazing pressure. Extensive work has revealed the roles of nutrients such as nitrogen and phosphorous in algal growth. However, mechanistic understanding of other physical factors’ impact on algal cells is limited. Here, we developed a platform that provides well-defined physical and chemical conditions to photosynthetic cells, with real-time imaging capabilities at the single-cell level. Our work revealed that algal cells’ growth response to light intensity can be described by the Monod or van Oorschot model. While furthering a mechanistic understanding of algal growth response to light, I have also started investigating applied approaches for controlling HABs. Here, I propose both a hardware and software approach to HABs control: ultrasonic treatment to disrupt and prevent HABs and an application to make HABs management more accessible to communities.