[banditpowdercoat]

A Herbie uses 2 pipes, One low down in the overflow, and one just above the "running" water level. ALL the flow goes through the lower pipe by way of throttling the Gate Valve. If the main drain gets clogged and can not somehow handle the flow, the level will rise to above the 2nd pipes level, thus letting the 2nd pipe drain. This will now cause a large gurgle, because it's a open pipe, which should alert you to "somethings not right with my tank"

I run this style of Herbie on my 150g Coast to Coast overflow and love it. Won't do a Durso again. Some do set theirs up so that the 2nd pipe takes a little trickle of flow. I see nothing wrong with this, other than maybe taking away from total possible 'emergency" flow.

I also have my 2nd drain, the emergency one, to drain with alot of height above my sump. SO even a trickle down my emerg. drain, makes a splashing noise in the sump, which alerts me before the level gets to gurgle height.