I have been using Every Circuit for a while. While you cant really simulate particular components (easily) it does allow you to simulate some trivial waveforms for basic circuits.
The liquid in the container would contain medium that contains chemicals that the microalgae need. Heres a common medium recipe BG-11 https://utex.org/products/bg-11-medium
Carbon is captured through photosynthesis and is stored as biomass. But when the microalgae dies the carbon is released again. So to truely store carbon the microalgae needs to be cultivated and buried / contained.