Problem relates to this
thread.
Drilled the hole for the 1" bulkhead (~20 minutes with dremel) and put the bulkhead and overflow in place and thought I would test before cutting into my plumbing.
Using a small submersible pump and measuring volume at 300gph found the bulkhead can't keep up. The layout how I planned is like the picture. If the drain pipe is submerged or even a short vertical piece at the end, I get pumping like in the video. If I just have the elbow at the end, the water in the tank backs up above the weir of the overflow.
Tried putting a Tee just after the bulkhead, just before the elbow, again the water level in tank backs up above the weir.
The refugium is a 20g and probably 300gph is a lot but really expected the bulkhead should be able to handle it. Any suggestions?
video
