Need to explode, not only dead creatures but also alive. Didn't you find that the jar for soaking live stones in the shop doesn't need strong light? Algae explosion is actually to let living stones explode low-grade algae to consume nutrients. Starfish, gobies, frogs, sea cucumbers, tube worms, hermit crabs, mantis shrimp, scallops and brain corals are all acceptable. Thick sand is closer to the natural ecology and cultivates microorganisms and fungi.