[Delphinus]

Either setup looks good to me, if you can get away with #2 that one edges out #1 because of the two sets of baffles - probably no way will microbubbles make it through all that.

I'm no expert on sumps but having built a few by trial and error, here's some of my key learnings (aka "things I wished I knew BEFORE building them").

1) Baffles take up a lot of linear space in the sump. For example my 110g cube is about 28" long (fits inside a 30" stand), and has two weirs (dams) and a baffle. I spaced them apart using 2x4's, so it only takes up about 4"-5" of the sump length but yet it's enough to really make for a tight fit with a filtersock and a skimmer and the return pump.

But if you space them too close, the water speed going vertically through the baffle section increases and the faster the flow, the harder it is to shed bubbles. Slow velocity is key.

So go as long of a tank as you can, and space the baffles far enough apart that you can get your hand in there (inevitably you're going to have to reach in to pull something out of there anyhow, might as well make it so that you don't hurt yourself in the process) and then they're likely far enough apart so to not create a fast flow through them which just carries the bubbles into the next section.

2) Level drops from one weir'd section to another create a waterfall effect which creates new bubbles. My first few attempts involved having the water drain into a chamber that was about 3/4 (or higher, in the case of my 75g sump) the height of the sump tank and then dropped down to about 1/2 for the rest of the sump.

So basically, just find the height that you want and size the dam/weir height accordingly. The baffle doesn't matter too much since water goes underneath.