If you research the life cycle, leaving the tank empty with out a host it dies. If you do that or empty the tank, let it dry out and use new sand and dead rock, QT anything live (rock, fish, inverts, coral, etc) for a minimal of 6 weeks, then yes, you will most likely be rid of velvet. If you start over, throw two more clowns in that have velvet, ich or something worse, you will be back where you started. Someone has on their signature..."the only thing that happens fast in saltwater are disasters"... It is very true. Sorry there is no fast, easy answer.