Maybe it's the other bits? Like sure a ton of photonic energy is available, but cyannobacteria need P, N, and other elements like Fe. In fact, I recall somethin

Maybe it's the other bits? Like sure a ton of photonic energy is available, but cyannobacteria need P, N, and other elements like Fe. In fact, I recall something about geohacking by just dumping a bunch of Fe into the ocean to do exactly what you're thinking...