Hole in 5gal setup

[Riverhawk]

Opinions folks.. Xtend reefwork or add a colony? This is my 5 gal nano that has a hole to fill.. Lights r coralife mini w/10000k and ac blue but can b supplemented.. Res r a sexy and a hifin goby and a tiny tux urchin..light is also supplemented by natural sun thru window.. Have shrooms pagoda xenia and hair rock...