for those with no space for refugium below right, i have a suggestion for u.. at the overflow compartment there, remove all the bioballs, its useless, need maintenance a lot. extend the piping to 1/2 to 3/4 of the tank height so there will always be much water in the overflow compartment. place a lot a lot of macroalgae there, as much as u can.
im very confident a bout this.most of the overflow compartments are as large as the hang on refugiums