Wow... never thought about searching YouTube. Such a prolific place.

I'm using it as much as Google now.
That guys video raises even more questions. What's the diff. between installing a bulkhead on the side or just bringing it in from the top? I guess you want to also think about how the water is being brought in so you don't create a massive amount of bubbles. He uses 4 baffles.
I noticed he takes some of his baffles all the way to the top. I liked the idea of leaving a little at the top for an ATO disaster contingency. Then any water that make be added b/c of a float valve/switch failure will have somewhere to go in the sump. Just let it overflow into your sump. I thought that was a good reason to get one of the 18-20" tall tanks too. If you run the water at the max. 9" height in the first area that will give you a lot of room for any overflows.
Is there some advantage to putting a bulkhead on the side as opposed to coming in from the top?
Is there some advantage to putting the return area in the middle?
I noticed he has water entering your sump from the right into the refugium. Even with your pvc with a bunch of slits in it I think it would still stir up your fuge quite a bit? Especially if you had sand in it. If you just had rubble rock probably be ok.
Seems most skimmers don't want to be under 9" of water. So 9" or less would be a good sump area water level right? I know you can always just raise the skimmer but I'd rather have it flat... maybe be safe and use like 6".
Why use acrylic baffles instead of just glass? I guess is stronger, acrylic is good too at a certain thickness. Glass can be sharper too.
I don't know if he uses socks. Not just socks... but what a block filter between some baffles... or bio-balls in there somewhere too. I guess water has to drip over bio-balls for them to work tho? I hear that they can be nitrate factories over time and aren't actually needed if you have a fuge.