In that small of a tank PC lighting is almost the norm due to size, heat, and cost. I have seen many types of corals SURVIVE in that light, but may not be exactly super happy with the amount of light. Putting the two types of corals as soft and hard is a bit of an over simplification. PC lighting in your tank should allow corals that need moderate lighting needs to flourish. I would avoid those corals and critters (anemones) that have higher light demands. I personally love the Large Polyp Stony corals (LPS) as they can be fed to help supplement any lighting issues.
I do run my refugium light at night as I have read that it will help any PH swings that occur during night time. I personally run carbon as I like the crystal clear water I get using it, but it isn't a necasarry item.
