I had much better longevity with the dwarf sea hares. The really small ones that were about the size of a quarter. I did have to keep sponges on my vortechs. The large sea hares never lasted more than a week. They would all bury themselves in the sand under an acan or other lps and the coral would kill them. The small ones avoided the sand bed, but I did lose a couple to acros as well.