I would love advice on a design I am considering for a new build. In my current build I have a smaller sump (ruby cube 20" Trigger sump) and run the refugium in the section next to the skimmer along with some live rock for good measure. What I don't like about this setup is 1). its tight and hard to get at equipment - for example I have the heaters sitting below an egg crate platform that holds the live rock, 2). the light spill allows algae to grow in unwanted places - skimmer, probes etc. For my new build I have room for a much bigger sump (going 36" long this time) and I have a cabinet directly next to the main display cabinet that can hold a 20" cube. My plan is this - I want to run the refugium in the cube cabinet in parallel to the main sump. The distance between the two would be roughly 10" or so, and they would be at the same level (about 2" off the floor). I realize that connecting two sumps this way is introducing points of failure but I have plumbed multiple tanks into a single sump in the past and it has been fine. My plan is to run a 1" return line between the two tanks (at around 1" off the bottom of both sump and fuge) , with a second 1" emergency drain going from the top of the fuge over to the sump. I would feed the fuge off a manifold using 3/4" connection for moderate flow. There will be a baffle in the fuge to eliminate bubbles and keep algae in the fuge (egg crate to ensure adequate protection against algae) Here are the main questions I have: 1). do I need 1" wide tubing between the systems or would 3/4" be enough?Any advice on best bulkheads to use to avoid leaking (BRS?). 2). where in the sump should I return the water too? I'm concerned about going back in too near the pump as I don't ant to draw water too aggressively from the fuge. 3). Hard or soft tubing for the lines between the tanks? I plan on also using union ball valves so I can disconnect the systems easily in the future. 4). does the main line from the fuge back to the sump need to be exactly at the same level? Are there any considerations I need to make that will ensure success and avoid some plumbing failure I am not considering. I'd love feedback and if anyone has some similar systems running, I'd love to see your designs or photos. As always thanks n advance for your input.