I use a CPR AquaFuge II HOB refugium on my 55. I run the 36W refugium light for 14hr, and my tank lights are on for 12hr. It provides a sort of "dawn/dusk" effect that I've been happy with for the past 6 months. Blocking all the light wasn't worth the effort in my case.
And no, you don't have to run a reverse photoperiod.