The skimmer I used on my ten was one of the biocube ones. I put it in my sump. You will prolly get a few responses saying the are a piece of #$%# but really I think they are just difficult to set up. they need to be in a place with medium flow, and a constant water level, then you can adjust the airflow to get the foam working. It took overnight for me until the foam rose to the collection cup, but after that it did work properly. It is a pain to set up, but it is super cheap, and works with a little TLC. It may not be as effective as the high priced skimmers but for a nano you probably won't need one as long as you mostly keep up with your water changes.