Refugium- live sand and rock, or refugium mineral mudd and rock??

crazy cajun

Reefing newb
im building my refugium and i have seen people use mineral mudd and most i see sand in the bottom whats prefered and why???
If I'm not mistaken.The mud is supposed to help by releasing trace elements and minerals over time.

With a deep enough sand bed ( 6"+ ) there will be a bacteria that builds up in the more oxygen poor areas of the sand that will convert nitrates into harmless nitrogen gas that will escape into the air above the tank.
You can use dry sand , the live rock you put in with it will seed the sand and make it live