no, you need to add a water outflow to the refugium otherwise how does the fuge get water. also you need to add a water baffle between the skimmer compartment and the return pump compartment then you are good to go.
I owuld just run both drains straight down , instead of combining them. one straight in to the fuge section and the other one straight into the skimmer section...that is the way mine is setup
I would go back to your 1st design with a baffle between the skimmer and pump section. And a ball valve on the intake into the refugium then you are good to go combo of your 1st drawing not pictured any longer and the last. If you know what I mean.
jon,
what size pvc pipe did you use oon your sump? 3/4"? 1"?
Should I be conerned with measuring the distance from pump to overflow spout when deciding on pipe diameters?
I have 1 " for drains and 3/4" for returns...mine is set up like your first pic. With the drains coming right out of the tank and into the sump. with the return in the middle into a ball valve then split to the return lines.