All that will do is allow the strong ones to survive. IME using FWE, the first dose was at suggestion strength. The second dose one week later was at 2x. Then I gave up on chemicals for the problem and got a pair of Blue Star Leopard Wrasses. Within a few days there was not a FW to be found.
You do have to be prepared to remove all the dead/dying FW's shortly after dosing. They can easily pollute the tank and deplete the oxygen supply so their prompt removal is very important.
And FWIW - even at 2x, I didn't lose a single fish or coral.