Help with overflow

[mark]

Don't want to be drilling another hole or taking a chance with a siphon so guess I'll have to life with <300gph.

Originally Posted by untamed

There's more...the water level in the red pail will also affect the flow you get through that pipe. (assuming that the exit of your pipe is below water line in the red pail)

Have tried with the discharge above the water level in the pail not any better.

Thought there would be a reduction from 600gph (rating for 1" bulkhead, gravity flow) if the bulkhead was horizontal but surprised it's half.