+1 .. I run one on my 20g. I get teased about it all the time too.
But it gets the job done, pulls out decent skimmate. I did the fishing line mod for the impeller and reamed out the air intake to allow a tiny bit more air in.
The one thing I don't like about it is how hypersensitive it is to adjustments. I run mine in the sump and I can't imagine running it as hang-on. I'd have emptied my tank onto the floor several times over by now if I actually used it that way.