jmo I wouldn't waste my time or resources on it ,, my thoughts on a refugium are ,, go big or at least a decent size ,, or go home ,, if space is limited ,, even if its not ,,, get a Algae Reactor ,, I love my Pax Bellum :)
I never did like the idea of hanging stuff on to the display tank anyway ,, jmo it looks cheap ,, cluttered ,, not eye appealing ,, even if its not a HOB Refugium and in the sump area ,, still takes up a lot of space for the amount of benefits from of it ,, I have friends that disagree ,, they have 20g to 30g Refugiums under their tanks ,,
The extra space I have in my sump tank area ,, I have a big sump tank ,, I like to get the biggest sump tank as I can ,, my display tank stand is longer than the display tank so that I can put a over sized sump tank under my stand ,, is filled with Bio Spears ,, a pretty good amount of them ,, I have always thought the pay off for the Bio Spears was better than the Refugium and I have the Pax Bellum ,,