My ext 170 will be 12" from the wall. Im building a 15 series 8020
Frame/cabinet behind and out both sides for my 10lb co2 tank, 15 gal ato reservoir, all power bricks, 4 ADJ power strips, and for my hybrid light fixture.
Skimmer controller, 6255 controllers, aqua logic heater controller, ato, and a ph-temp-sg monitor.
You can do alot with the 8020.
This is how I plan to mount my 10 power bricks.
My aquatic life 48" hybrid will be adjustable from zero to 14" above the tank, I will run it at 8", and I will be able to slide it back 14" to work in the tank.
I will start a thread eventually, lol.
