Hang on refugium for an sump?

[Troyntu]

Hello I have an RS-300 sump for my 180g and there is no room for a refugium. I know I should of bought the right sump for the setup but it’s what I have now

my question is there some hang on type of deal I can do or something someone has done for an add on refugium for a sump on the bottom? Thank you. I plan on doing cheato

 

[Spare time]

Hello I have an RS-300 sump for my 180g and there is no room for a refugium. I know I should of bought the right sump for the setup but it’s what I have now

my question is there some hang on type of deal I can do or something someone has done for an add on refugium for a sump on the bottom? Thank you. I plan on doing cheato

Fijicube and CPR makess HOB refugiums as well as others. There are also algae reactors (pre made or DIY).