I would let the tank settle if your losing fish. Second I would qt new fish to make sure they are good and don't infect your old tank inhabitants . I would recommend drip acclimation for new fish. I have done both and never any issues with just floating. Maybe they were sick from the get go, in a qt you can keep a close eye on them and see if anything goes wrong quickly and clearly.
Good luck and dont give up I have had many failure in the reef hobby and it is very rewarding. Have patience it will work out.
