I've been running a HOG.5 since Jan on my nano cube 28 with CF lights and 2 RBTA, 3 fish, sofites, LPS, a few sps, macros and a few snails. I have not changed my water for 2.5 months and my water quality is still great (nitrate 0.2 (salifert) and phosphate at 0.018 (Hanna Phosphorous checker). Obviously, I need to dose Alk and Ca.
I don't run a skimmer and have live rock, purigen, and occasional carbon and phospban in a sock for filtration. I'm planning to quit carbon, phosban and purigen and I'm hoping to see similar results.