minimum water height above herbie style overflow drain?

[sayn3ver]

i like the Herbie method of draining water to the sump. Its silent which is what i prefer. However, i don't have a tank setup to experiment for the minimum amount of water needed to prevent vortexes from forming above the drain. I am trying to setup an extremely shallow tank, somewhere between 6- 8 inches tall but still want a sump. I've used a herbie briefly before on another setup but had a good 8+ inches of water over the main drain.

 

if the tank is only 6-8 inches tall water in the overflow box would only be roughly 4-5 inches which i feel if the bulkhead was mounted on the bottom of the box would not be enough to prevent those little tornadoes from forming near the surface.

[JustReef]

I would think 4-5 inches would be enough. You just have to keep the air out.

 

I'm actually filling my new tank tonight. I'll mess with the Herbie overflow and let you know.

[sayn3ver]

I would think 4-5 inches would be enough. You just have to keep the air out.

 

I'm actually filling my new tank tonight. I'll mess with the Herbie overflow and let you know.

 

thanks just reef. i will be looking forward to the results. You may be saving me a lot of grief.

 

[Bobalouy]

It depends alot on how much water you are trying to put through it. You can also put a ball valve on the drain line so you can slow the falling water down some.

[sayn3ver]

i will be shooting for a 3x turnover rate of the tank.

[JustReef]

ok, I played with my herbie oveflow a little bit.

 

My primary drain is a 1" bulkhead on the side of the tank near the bottom it has a strainer on it. Different configurations may give different results.

 

I reduced the water level in the overflow box to 1" and didn't have an vortexing or noise from the drain. However having the water that low caused a lot of noise as the water fell down the overflow box. It seems like the sweet spot was about 3-4 inches below the overflow teeth.

[sayn3ver]

sweet dude, thanks. So if the overflow itself is only 6 inches tall, and the water level is 4 inches high, i should be alright?

[JustReef]

I think that would be perfect, but you might have to adjust it slightly to make sure it's silent.