The diatom feed on silicates in the sand/rock you started with. Once the silica is gone (usually a week or 2) the diatom will be gone as well. As long as you don't add sand/tap water/or anything else with silica...you should never see diatoms again. Just wait, and it will disappear - happens in all new tanks. As far as skimmer - I have an aquaeuro nano skimmer in my JBJ 28g cube. It's fairly quiet...but not the best skimmer around either. Once broken it, and adjusted (lots of trial and error) it does okay though.
Larry Wheat
President/Co-founder "A Butterfly's Touch" and "Running4Trisomy"
90 gallon mixed reef