I would do some seriosu water changes before putting them back in. You can get a mini cycle from when you move the existing sandbed which is probably what happened in your case. Where are the fish now?
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.