Then imo, the only thing you should have in there is a ball of chaeto and a strong light. For this purpose, I would suggest you move the refugium to hang on your sump instead of the back of the tank so that light leak from the fuge won't bother your tank. Lights on chaeto can be run up to 18 hours a day, and reverse cycle as the tank is would help increase overall daily pH. The ball of chaeto should be allowed to freely roll in the fuge, and should be trimmed regularly to prevent it from overgrowing. The chaeto sucks up the nutrients, and when you trim the chaeto and remove a portion you are removing those bound up nutrients from the tank.

Imo, a DSB in that small of a tank would not be helpful for reducing nutrients.

Thanks Myka, I think I'll do just that.