I have been running a salt water tank now for 3 months, i have 3 small fish & a arrow crab. I have been waiting to buy a algae eater till there was plenty to go around. On the back glass the algae is green hair with some rust color patches but on the gravel of the tank it looks BLACK I went & bought 2 turbo snails & placed them on the biggest patches they started to eat it, but then our anemone died & took the snails & arrow crab with it, 3 fish are fine. I though the anemone killed all the invertabrates but i bought a arrow crab & 2 more snails & the snails have died. Is it the BLACK algae or bad luck?