Herbie overflow

[Andreanegri96]

Hi everybody, I have a 90x50x50cm tank with a 50mm hole where I've mounted the original (and quite noisy) overflow. Now I'd like to change it and mount a DIY Herbie overflow (all commercial ones have a 40mm or 60mm mounting hole) where I'm planning to mount 2x 32mm drains: primary with a regulation valve and one for emergency.
Can someone help me understand what measurements the box should have?

 

[lapin]

This might help
https://gmacreef.com/herbie-overflow-reef-tank-plumbing-method-basics/

 

[Andreanegri96]

This might help
https://gmacreef.com/herbie-overflow-reef-tank-plumbing-method-basics/

First of all thank you for the informations, but I have few questions now:

- Herbie overflow works with two drains: one fully submerged by 6"/15cm of water (correct?) and a second one for emergency. I see that the correct level of water to avoid noise is up to the top of the emergency one, but water should not drop inside of it or just a little quantity should go inside it?

- The main hole that connects the tank and the box of the overflow has to be fully submerged, right?

- Is there any minimum dimension for the overflow box or it just needs to fit the plumbings?


Thank you so much

 

[lapin]

First of all thank you for the informations, but I have few questions now:

- Herbie overflow works with two drains: one fully submerged by 6"/15cm of water (correct?) and a second one for emergency. I see that the correct level of water to avoid noise is up to the top of the emergency one, but water should not drop inside of it or just a little quantity should go inside it?

- The main hole that connects the tank and the box of the overflow has to be fully submerged, right?

- Is there any minimum dimension for the overflow box or it just needs to fit the plumbings?


Thank you so much

It’s fine to have a little water going down your emergency drain.

The hole does not need to fully under water. Think of an overflow box that has slots for water to enter and to keep out snails and fish. The main thing is to keep the level in your box constant.

Just needs to fit the plumbing. The smaller the box the harder it will be to control any return pump fluctuations.

 

[Andreanegri96]

The hole does not need to fully under water

So it doesn't matter to fully cover the hole but the important is to keep the right level of water in the box in order to keep the main drain submerged, right?

The rest is quite clear