How much can a 1" bulkhead flow?

[mdc860]

I have wondered if the limitation to flow is not so much the bulkhead (I'm impressed with Neutical's math), but rather is how much flow you can get into the overflow box- The number I see most often is 600 GPH for the usual overflow- I know there is away to calculate flow over a weir, in that our overflowws with rectangular slits are basiclally a group of small weirs draining the tank.

[Neuticle]

I'm currently flowing an estimated 700+gph, with my QuietOne 4000 @ 3.5'. The biggest factor in flow is going to be the length of downtube below the bulkhead, longer than two feet and it will siphon like mad.

My overflow system can take much much more than this, it's 26" tall and only has 4" of water in it. If Mag 12's weren't so hot I'd get one...

[mdc860]

Do you find the noise of the water falling down your overflow to be objectionable? I imagine that a 22" waterfall must generate some decibels-

[Neuticle]

No, it's running down the sides of the overflow, so it's nearly silent. My cooling fans are much louder.