nope its fine. i had a remora (rated 75) on my 20 for a year, now its on my 29. i think its actually recommended to get a skimmer rated for a certain percentage higher than your tank size. not sure what it is, though.
well actully i found another one i want. its the coralife neddlewheel skimmer rated for 65 gal. if any you guys have one could you tell me how you is set up.