I'm with BeenGirl when I ask why are refugiums bad? They can lower nitrates (not much, but better than nothing), a protective space for pods
and macroalgae to grow, and can help balance the tank if you have a reverse light cycle. During daylight hours, plants release oxygoen and in the darkness plants release CO2
and use oxygen. Same for corals so if you switched the lighting, the refugium marine plants would be giving off O2
during the night and the corals would give off CO2
balancing it out somewhat and vise versa.