Be careful of anything that kills sandbed and rock bacteria: it will increase the waste in your system while diminishing the capacity of the system to deal with waste. Rock and a hard place on this.
If it were mine: I'd bite the bullet, buy a tank adequate, and put all fish into it, bare bottom, no rock, no sand, with a plain floss pot-filter [really potent pump in bucket with floss atop, changed daily] and go hypo with them, with the ATO on this tank, leaving the big tank fallow, but all corals and life left in place. Then put the bought-tank on the sale forum and recoup some of your cost. The floss will grab any parasite that falls off the fish and is daily tossed.
OMG, just noticed you're using Prime: USING PRIME WITH CUPRAMINE CONVERTS CUPRAMINE TO A COPPER THAT IS 10X MORE TOXIC,---WARNING!!!!!!!!!! do not use copper in treatment.