Nice work...i like the latest version of rock placement. You definitely want to leave enough room on all sides of the glass to get a mag-float through....unless you plan to have coraline cover some of the side glass. I have had my 12g nano for 9 months, and have been through every configuration of filtration known to man. So many choices for those 4 little compartments... I will tell you what has finally worked the best for me in terms of stable water parameters.....stable being the most important factor in keeping your inhabitants alive. Number 1 chamber (from left to right)....PolyFilter....best stuff money can buy. Second and third chambers....nothing but water. Fourth chamber.....upgraded pump from stock to maxijet 900...dropped right in...much better flow now. Also equally important is to do at least one 20% water change per week. This routine has yielded a very stable environment for my livestock. Good luck...and keep the pics and questions coming.