Yes, but there are other benefits to having a few fish in that frag tank in the form of pest control. If you copper quarantine any new fish or buy them already quarantined like Dr reef, you don't need to worry about ich. Adding a few flatworm/redbug/nudi predators like the springeri damsel or sixline wrasse could stave off an outbreak before it wreaks havoc if a dip misses an egg.Would dumping skimmate from a heavily loaded fish system be a solution?
I am working very hard to keep my achillies from catching ich and that is why I have kept my frag system fishless for the last year.