Got it! Thanks!You are pretty much into preference rather than best practice territory so reviewing more tank oriented literature or forums for ideas and experimental results will give you a better idea of how you may want to proceed. Some people really like their refugiums to be small display tanks, some use their sumps. I gave up on using the sump as a refugium because of the additional work and lighting requirements. If your refugium is also your sump I would recommend not using sand to avoid complications with the pumps.