Description: 43 Gallon Octagon with a 15 gallon homemade eco-system style refugium/sump (deep sand bed, chaeto, and live rock) and a algae waterfall style supplemental filter. I have had no skimmer on this system for well over a year and no longer have to do water changes. Nitrates and phosphates are 0 and seem to be staying there. My system has in-line UV (now rarely used), 150W 20K metal halide lighting, live rock straight from Fla. to my tank (no "curing"), rock is mounted on a PVC frame as the arrangement is vertical, 2 Koralin and 2 Maxi-jet power heads.
Advice: Design your system around the creatures you want to keep and try to use nature for filtration as much as possible rather than mechanics. Either build an eco-system or you will give yourself a part time job every weekend.
I would not advise an octagon as a first reef tank as lighting and arrangement is very difficult.