*Deep breath* Okay, bear with me here- I'm a newbie with a lot of questions! I'm slowly putting together a 120g build and I did a search for 40b sump plans and got a lot of ideas. I measured the stuff I have, and I *think* I've figured out something that might work, with some clarifications from the pros. I want to do a three chambered design: a drain/skimmer section, a refugium, and a return section. First off, how close can the skimmer be to the filter socks? Does it even matter so long as you have room to switch out the socks and empty the skimmer cup? How deep should I make the return section? And my heater is an Eheim Jager 250W, which is longer than a week of Mondays- 23" I think. How in god's green earth is that going to fit? If I need shorter heaters to fit in my sump, what do you recommend? To explain the pictures: the drawing is an approximation. It's mostly drawn to scale with each square =1" but the dimensions of the equipment are estimated. I do know the skimmer footprint is about 9" and the return pump is about 4". I figured the return section should be around 8" so I have room for the ATO, to maintain the pump, and to keep the water level as consistent as possible. Good idea or bad idea on the 8" section? And how far apart should the two baffles be? I drew them in as being 1" apart, with a 1" gap on the bottom of the floating baffle. The baffle between the skimmer and fuge is at 10", mostly because I figure I can raise the skimmer if needed, but it'd be harder to raise the baffle if I put it too low. In the photos, the orange mat marks the first section, the red mat marks the fuge, and the return section is marked by the fuge-side edge of the boxes. Measurements of the sections are approximately 15" for the sock/skimmer section, 12" for the fuge, and 8" for the return. What are your thoughts? Am I missing anything obvious, or planning something wrong? Thanks for your input! Oh, and what thickness of glass should I get for the baffles?