Excellent! A well-planted, well-established refugium will be a very nice asset for both your seahorses and a Mandarin goby, Tammy.
Just make sure that you obtain a captive-bred-and-raised Mandarin and your Dragonet should do well. Provide him with his own Mandarin diner and stock his feeding dish with chopped Hikari Frozen Blood Worms, Nutramar Ova, and New Life SPECTRUM Small Fish Formula pellets that the Dragonet can feed on at his leisure. That way the copepods and amphipods from the refugium should suffice to provide both the Mandarin and your ponies with an opportunity to graze on live treats between meals.
Pete Giwojna, Ocean Rider Tech Support