Ereefic,
Beautiful tank.
I'm wondering why you didn't go with spaflex plumbing under the tank (for the drains and returns). It would have done away with all those 90 degree elbows there. SPaflex is very easy to work with. IMO, you could have routed the spaflex directly down from the overflows/returns, and snaked it to the holes going downstairs through the floor.
Another thing, did you purchase the AGA overflow kit, or get your own bulkheads? I ask, because I found the AGA overflow kit was very restrictive. Using their fittings was bringing down the size of the drains and returns from 1" to 3/4" and 3/4" to 1/2" respectively.
I machined my own fittings to make optimal use.. check it out:
I machined off the "elbow" from the Fitting-Thread adaptors so that I could slide the bulkhead's nut over the fittings (for future removal if need be)
Here's how they look installed:
Another shot (with plumbing):
A shot of the plumbing (using spaflex) during initial setup of the reef. The pump on the floor is a Sequence DART, used for the closed loop, going to 3 ReefRat rotating returns on the tank. The overflows and returns go to/from the sump in the other room.