In tank refuge?

So my 100g tank has been up and running fish only for almost a year now with no problems. I upped the ante 100 fold last week when I added 5 AI Sol Blue Led's on top of my 4 foot long aquarium. I'm planning to increase the amount of load from livestock in my tank and to add corals. I've been thinking a refuge would be good to chaeto in to help reduce nitrates and possibly harbor amphipods & copepods. I do not have room in the cabinet or in the sump to accommodate a refugium. What I have in mind is something I could possibly hang on the side or place inside along the back of my aquarium. It would be nice in this case to be able to make use of my new Led's as well. Does anybody have any ideas? Thanks.