Emergency Drain Height on Herbie Style overflow

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rob taft

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I'm new to sumps so forgive the question.

How far above or below the Weir does one place the emergency drain on a Herbie style overflow? I've seen where some place the drain opening about a 1/2 of so below the weir thereby allowing some amount of water into the sump and other placing it just above the weir so it won't receive any water unless the water rises in the overflow. My thought are to the latter and not the former i.e. but I've seen both advised
 
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homer1475

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I have mine set to set the water height in the tank. I have a rimless tank and like the water level high. So the height of my emergency dictates the height in my display(center tower style overflow).

I also do not like the sound of crashing water, so the higher my emergency, the less fall into the overflow the water has.

I don't think either way is wrong, it's just what you prefer.
 

Montiman

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I'm new to sumps so forgive the question.

How far above or below the Weir does one place the emergency drain on a Herbie style overflow? I've seen where some place the drain opening about a 1/2 of so below the weir thereby allowing some amount of water into the sump and other placing it just above the weir so it won't receive any water unless the water rises in the overflow. My thought are to the latter and not the former i.e. but I've seen both advised
I find it pretty much impossible to tune a herbie with out some flow through the secondary drain. That being said if some flow is going through the secondary drain a better question is where do you want the water level in the overflow box as the height of the secondary drain is what determines the water level.

I have found that I want the water level in the overflow box to be just below the weir teeth. if the water level is above the teeth it will reduce the surface skimming from the weir. The lower the water level in the overflow box the more noise comes from water falling down the overflow box. Thus I like the water level in the overflow box as high as I can while still being slightly lower than the weir teeth. Since this is where I like the water level this is where I like the top of the emergency drain.
 

homer1475

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I find it pretty much impossible to tune a herbie with out some flow through the secondary drain. That being said if some flow is going through the secondary drain a better question is where do you want the water level in the overflow box as the height of the secondary drain is what determines the water level.

I have found that I want the water level in the overflow box to be just below the weir teeth. if the water level is above the teeth it will reduce the surface skimming from the weir. The lower the water level in the overflow box the more noise comes from water falling down the overflow box. Thus I like the water level in the overflow box as high as I can while still being slightly lower than the weir teeth. Since this is where I like the water level this is where I like the top of the emergency drain.
Said much better then I did, but basically how I do it to.
 

ca1ore

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Noise is an issue, but you ought to also consider emergency capacity. If you have the latter too high up, then there may not be any room for head pressure to build up and the emergency will fail to handle all your flow in the event of a major problem. A way around this is to upsize the diameter of the emergency stand pipe. Probably nothing to be done about the size of the bulkhead, but I always use adapters to get at least two PVC sizes larger. On my current tank, the emergency is a 3" standpipe over a 1 1/2" bulkhead. You may never need 100% from the emergency, but having one that cannot handle that much rather defeats its purpose.
 
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newbie2014

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Do you suggest having a gate valve on. Other the main drain and the e-drain?

The seasoned reefers can probably guide you better.........

Eventhough I've been reefing for a few years, I just started my first tank-sump setup as of this January. It's a rimless 60g cube with single drain (durso) corner overflow. I converted it to a herbie with 1" main drain and 1" emergency drain. The main drain stands about 12" and the emergency about 1/4" below the overflow weir, respectively. I put a gate valve on the main drain to regulate the height of the water in the overflow.
 
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