First reef tank! Questions! Questions! Questions!

Hi I'm starting my first reef tank, I already have a 29g saltwater for fish and few corals. This new tank is going to be all coral though, and only 12g with a 10g sump. I've got the idea of how the sump runs and ordered the parts and had the chambers sized. Hopefully my idea of how it works turns into it actually working, BUT my question is do I need a refugium? I have always wanted to try a mandarin goby, and since it will be a small tank I will have soft coral, so would having some hair algae growing in a refugium with some reef bugs be helpful?

I have seen mixed reviews on here for them, so for my situation what do you recommend?
Thank you so much!
Becca
:dance: