I acclimated mine for about 2 hours before putting him in and haven't had a problem with him.
it's been about 4 months so far. I happen to really like the sea hare so I can't recommend against getting another one. just make sure you have enough algae for him to eat.
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.