Hi! I recently set up a 5.5 gallon nano reef and am thinking about eventually adding a tuxedo urchin. I will wait a few weeks to make sure the tank is stable and there is a lot of algae (though the tank is already finished cycling), but would I be able to add one? If so, would I also be able to have two red legged hermit crabs and two trochus snails? I already have the trochus snails but I have not gotten hermit crabs yet and don't know if I should. I would much rather have a tuxedo urchin if I can't have both. Would both fit, would I only be able to have the urchin, or would I not be able to have the urchin at all? And regarding algae, if there isn't enough growing I can feed the tuxedo urchin nori so my question is if 5.5 gallons is enough for the urchin to survive and do well, not if it's enough to generate enough algae for it. Thanks!