Dual Overflow Question

[ph2505]

Planning out a build, had a question about the plumbing of a dual overflow. i am planning to have 2 island overflows with 2 holes in each, total 4 holes. I am planning on having 2 return lines, my question is, are you able to split up a Herbie style overflow or do the two pipes need to be right next to one another?

Overflow 1:
- 1st return pump line
- Herbie full syphon drain line

Overflow 2:
- 2nd return line
- Emergency drain pipe

would make sense you could split it up but just want to see if anyone has any experience with this? thanks

 

[WvAquatics]

Following

 

[Dread Pirate Dave]

I was wondering how this would be set up for an Aqueon 120, replacing the dursos. The problem is that water is going to spill over both overflows and the emergency one will fill until it overflows to the sump. (hope I said this right) I could be wrong though. Needs more thought. lol

 

[ph2505]

Bump

 

[likemike99]

just asked same question. I was thinking if the one side was doing fine then the side with the overflow would not have any real circulation as the water is only going to move if the first one is not doing the job.

 

[Vivid Creative Aquatics Verified Sponsor]

It might be easier to just treat both as their own drain and will likely accomplish the same thing

I used t have a tank with dual mega overflow on the back wall - each had a return and a drain. I treated each side as its own drain but tied them together to a larger single pipe just before entering the sump. Each drain had its own ball valve before the two drain lines where merged to control siphon and noise separately for each.

If one drain got closed off, the other one was able to handle the flow - all be it at full capacity. You just need to make sure you not running at full capacity for both drains.

 

[WvAquatics]

I have been watching thos thread as i am about to plumb a 180g reef ready. I finally settled on running both drains herbie style. 2- 1" main drains ans 2-3/4" emergancy. Im just running pvc up the back for one return. I have a hood so return wont be seen in normal operation.

 

[DCR]

There are some challenges to only having one drain in each overflow box with regard to balancing the flows. The one with the full siphon only will not have any surface skimming and it will be difficult to control the level below the level in the tank. The one with the emergency will end up being stagnant unless you make it a secondary continuous drain. I have never attempted to drain two overflow boxes but if I had to I think I would make a Herbie in each one and run the return(s) over the top or drill and extra set of holes on the back for the returns.

 

[deome]

Planning out a build, had a question about the plumbing of a dual overflow. i am planning to have 2 island overflows with 2 holes in each, total 4 holes. I am planning on having 2 return lines, my question is, are you able to split up a Herbie style overflow or do the two pipes need to be right next to one another?

Overflow 1:
- 1st return pump line
- Herbie full syphon drain line

Overflow 2:
- 2nd return line
- Emergency drain pipe

would make sense you could split it up but just want to see if anyone has any experience with this? thanks

I've got a little experience with creative plumbing, and the more I look at this, the more I think you absolutely *must* have both drain lines in the same overflow *if* you want one to function as an emergency drain. The emergency drain is only supposed to drain if the Herbie drain clogs; a clog will cause water to back up in the overflow until it rises over the emergency drain hole. If the emergency drain is in another overflow, then the emergency drain overflow will just fill with water up to the top of the emergency drain pipe until it becomes a full siphon (or overflows the weir if the pipe rises above the overflow weir). Basically, putting a drain in an overflow by itself prevents its use as an "emergency" drain--it will either function like a regular siphon drain, or it won't work at all.

You could do two overflows, each with a full siphon (Herbie or whatever), and that would provide some redundancy, though it would be difficult to detect a clog in either line (maybe if you put a flow meter on each drain line?); the important thing about this setup is to plumb each drain to the sump independent of the others. However, again, neither would function as an emergency drain.