i didn't used to have a skimmer, i used to do 10% water changes every three days but when i went on holiday a lot of my corals died because the nitrates rose. then i got a deltec mce300 for my nano 70L tank couple of months ago. it works wonderfully, its in my bedroom and hasn't caused any problems for studying or sleeping as it's virtually silent. it pulls out about 150mL of gunk a week, and my nitrates are at zero as far as the test can show... id really recommend a Deltec, they're brilliant!
i now know that i can go away for a week and my tank will be fine.