And for what it is worth, I'm in with Gflat. Watch the in's-vs-out's.
As my tank has aged, it's out's are not up to it's in's with no parameters changed (they were initially). If possible oversize the out's, for what ever reason they always slow over time.
Just had to tear down my right side out line because it could not keep up. My overflow kept filling to a non-flow point. I found nothing, but it was slower than it should have been (or was for that matter). I replaced all 90's with double 45's and it helped, but the right side is still quirky.
Both my out's are reduce by 1/2" from possible max size, and I'm now thinking about a total rebuild of the outlet side to go to max size.
This far down the road, it's a PITA at best. Do it now, before time (and hassles) catch up with you. Make drain lines as big as possible, don't reduce them. Outlet controls are a piece of cake, but reducing you're inlet flow causes mental anguish.
Best case, you can up the inlet flow, as is my case, you have to reduce their flow for some time produced (unknown) reason.
PLEASE; all responses to this opinion should be started in a new thread, I don't want to take this one over.
Somehow, I just know people will have opinions.
Rick