I take mine apart about once a month for cleaning. About every three month's I'll place it in a 5 gal. bucket with water and vinegar (3:1) and let it run for an hour or so.
+2 I do that with my BM NAC7 as well.
I should probably order a backup pump for mine too. It's been running great for a long time (still using the original mesh wheel) but I hear plenty of bad stories about the atman pumps to not be prepared.