I think most guys don’t quarantine corals. I’m actually going to start now that i have an extra reef running. It will be specifically for mariculture sps colonies that I like, but that I’m afraid to put directly into display.
As far as duration of qt, I think it’s subjective to the reefer and coral type. I plan on qting for at least 6 weeks (possibly a lot longer), not only do several dips and observe for pests, but also to let the coral regain zooxanthale, polyp extension, and overall health.