Split drain or split return?

[scherzo]

@Anthony - eek! at least I had the forethought to run it externally.. will that help? I can also easily change it out with something else. - Do you have anything kicking around. (BTW.. The skimmer I have is your old Euroreef RS100 .. bought from someone who bought it from you!!)

As for sump design. I did check out Melev's Reef for designs. I'm actually using his 80 gallon design (slightly modified) because I need (want) to maximize my refugium section since my sump will be viewable. I will be able to have slow flow through the refugium if I want.

I also have an unfortunate size for a sump (48 X 16 X 24.5 H) so I have a strange layout. My refugium section will be (36 X 12 X 24 H) - about 45 gallons.

[mark]

I'd be looking to keeping the drain as quiet as possible using something like a Herbie (with one drain having full flow and the other drain dry).

Wouldn't get too worried about an exact turn over formula through the sump but often see the gph rating of the skimmer being a minimum but nothing wrong with having the return flow contributing to the overall turn over of the display.

Again my focus would keeping things quiet.