Found the hawkish
Copied from my build thread
He was in the sump!
One of those things you use to control the water level in the overflow (J shaped- can't remember the name) had come out of the bulkhead and the overflow was drained out. When I checked the overflows I put it back, but didn't think about him possibly having gone down into the sump (until @tbrown asked about it). I just called my wife and the boys found him and returned him to the tank.
Copied from my build thread
He was in the sump!
One of those things you use to control the water level in the overflow (J shaped- can't remember the name) had come out of the bulkhead and the overflow was drained out. When I checked the overflows I put it back, but didn't think about him possibly having gone down into the sump (until @tbrown asked about it). I just called my wife and the boys found him and returned him to the tank.