instead of HOB filters, i would perfer sponge filters. easier to use.
I would agree with this for a smaller tub like you mentioned. All of mine are at least 30g and most are over 50g. A sponge filter isn't as efficient in a tank that size although if you have a smaller bio-load I can still see it working. I use HOBs mainly because I have several hanging around more than any other reason.