Drain setup: General Questions

[wingedfish]

I can't really understand your picture but if you have no overflow and your main drain is underwater, then in the case of a power outage, it must drain down to the pipe level. If your sump is large enough, then your good.

[eli@fijireefrock.com]

I cannot understand your photo to.
if you are running a system without an over flow box then one drain pipe should be slightly lower than you second (emergency) drain pipe.Simply like wingedfish said when a power outage happens your tank water will drain to the end line of opening in the pipe.
This setup will remove surface water but will create allot of noise.An actual picture of the setup would give us a better overview of what you have.Bottom line is best to get an overflow box going.