it depend on what your goal is for your refugium.. general rule is the bigger the better.
for a 10gal display tank, imo, a refugium won't do anything. Unless you have a hidden 50gal fuge or something. It won't provide enough pods for any pod demanding fish. The small chaeto won't provide much nutrient export either.
it does add total water volume to your tank, that's a beneficial part
but definitely wait and hear some other's expert opinions on this..