ACS keeps on top of the number of coccidia without killing them, which is what you want. The birds will develop their own immunity to coccidia but need not to get too many too soon as this is when they get ill.
If you need to actually treat an ill bird, don't bother with Coxoid, use Baycox instead. Coxoid is a coccidiostat only -stops the growth but doesn't kill them, Baycox is a coccidiocide - kills them. And yes, in these circumstances, disinfecting things to reduce the number of oocysts about is a good plan.
Personally I prefer my chicks to have ACS feed, having nearly lost one set of youngsters to coccidia some time ago.