Jay, I've got a 10 gallon nano with a 5 gallon bucket for a sump at the moment until I can get something that fits in my stand.....I have a HOB cpr skimmer on it, no other filtration. I just did a water change today, and it's been a month, and everything was still looking great. Skimmers that are marketed for nano tanks, IMO, are not worth it. If you're going to do a skimmer, I'd recommend getting one that's overkill for the tank. If nothing else, it'll definitely help keep your water cleaner and your critters happier. My tank did no where near as well when I just had a filter with carbon on it and no skimmer.