Herbie In A Marineland 180 RR Question...

[TruRacr314x]

I'm in the process of setting up my 180 and am contemplating a Herbie overflow. This would use the corner overflows for the drains (one full siphon and one emergency) and the return would come over the back. I have read quite a few threads describing the setup/plumbing of this...but I need some help understanding one aspect of it. In a Marineland 180RR tank...the overflows have a lower set of vents for added circulation (they say it helps pull water from the bottom). It appears most people put the full siphon 3-6 inches under the water line to keep it from grabbing air. When power is shut off to the return...instead of just draining the overflows down to the siphon....wouldn't the lower vents allow the entire tank to drain down to the full siphon level? This could easily drain 30-40g into your sump? Or am I of the wrong thinking? I can't believe I have not seen this discussed anywhere yet...

Any help understanding this is much appreciated!

 

[TruRacr314x]

Anybody?

 

[TruRacr314x]

Nevermind...I guess I should have taken a closer look at the tank before posting. Someone on another forum enlightened me to the fact that the lower vents go through to a false wall that leads up towards the top of the overflow. Now I can move forward with the Herbie plans!