Overflow OK?

[aeri]

just built my 1st overflow...
does it look ok? i've checked a few other overflows on the forum and noticed that the vent pipe is usually placed higher than the rest of the overflow.
would mine suffice? what purpose does this serve exactly?

 

[cypher1024]

The Vent pipe just needs to be higher than the water level in the tank (i.e. higher than the intake). Since yours reaches up to the bottom of the topmost horizontal pipe, you'll be fine.

Without the vent it would be a syphon, not an overflow.