i have one currently on a 10 gallon.i will be moving it to a 20. i dont really recommend it for only 3 reasons,its big, its noisy without a doubt(when the skimmers on),and it blasts millions of bubbles into the main tank. though it keeps my water really clean,and it is powerful and made for saltwater use. so its mostly a so-so filter for skimming,mostly the filter is good,oh and one more thing if you buy it place bio-balls in the main house for extra filtering.wont stop the bubbles though.
good luck