I currently have a 75 gal display w/ a 20 gal sump(filter bag, skimmer) the only size of refug that I think will fit under my tank is 10-15 - is it worth the time and money for a 10-15 gal refug?
My 75G has a 30G sump/refegium. I wise I used a 20 long so I could get it out sometimes but too late now. I feel like I could have fit it in a 20g. I keep mine very compact. I see them soimetimes in a whole 10G and only 1/10 is full of algea. Looka like as wast of space to me. PLus I know that you can use a small rubbermaid bucket. Flexable to remove and just add lighting. I highly sugest a refegium and I know it's saved my but with being new to the hoddy.
I used to run a 20 gal sump/ fuge under my 75 tank before converting it into a refugium and it was very sucessful. Since I wasn't using another sump, the refugium part was probably barely even 10 gals.
Any size refugium can be a positive addition...especially if it is properly set-up. Even hang ons can be of benefit in some applications. I'd encourage you to develop the 10-15 gal refugium if thats all the space you have available.
...and Thomas...great idea...my 55 gal refugium and 30 gal sump are in the room behind my display. If there is ever a problem with either access is real easy...and either can quickly be shut off without disrupting the overall system.