One of my customers has a 125gal reef tank that is over run with bristle worms and some are even 1ft+!!!!

I know the problem is she over feeds. I have tried to put sixline wrasses, eightline wrasses, arrow crabs, etc. To get rid of the worms apparently from my last chat with her though the worms ate the fish and everything! Even her darling seahorses! Now she is asking me to start it over. I was going to replace the sand and freshwater dip the live rock.... any better ideas or things I should try first? I have never seen an infestation this bad before
