Best Way to Set Up Dual Overflows

[CarrieB]

I've bought a used 120 to replace a tank that self-destructed while I was on vacation. The new tank has dual overflows. Each overflow has two 1" holes drilled.

There doesn't seem to be an obvious best way to plumb two overflows so I'm looking for people with experience good or bad. In fact, if you hate how you plumbed your tank, I'd really like to know that. If you were really clever, that would be useful too.

FYI, the old one was plumbed as a Herbie and I liked that a lot.


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[JMorris271]

Herbie works best for the dual overflow tank. My tank has duals. In each one, one hole is 1 inch and the other is 3/4 inch. i use the 1 inch as the ED and the 3/4 as the full siphon drain . You are lucky in that all of your drains are 1 inch

 

[CarrieB]

So you basically have two Herbie setups and run the return over the back of the tank?

Any issues tuning the system? Have you got a gate on each side?


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[kmbyrnes]

Or run a Herbie on one side, with a return and a full siphon for the other.
That's how my dual overflow tank is plumbed.

 

[davehead86]

Run it like a bean animal. Just plug one hole. One side is the full siphon and emergency drain. Other side is the plugged hole and the return pipe.

That's what I would do with duo overflows.


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[Bl4ckDr4g0n]

http://gmacreef.com/herbie-dual-overflows/

I found this site to be very helpful

 

[JMorris271]

So you basically have two Herbie setups and run the return over the back of the tank?

Any issues tuning the system? Have you got a gate on each side?


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Yes, my return runs over the back of the tank. I have a gate on each siphon drain and on the return line.I wouldn't call the tuning process a problem issue. Took 2 of is 45 mins. Having 2 emergency drains takes all of the pressure off of you about having a tank overflow in case you have the pump working faster than your drains so you have time to dial it back or open the drains more .It is imperative if you have someone eye balling what is going on on the top of the tank while you are turning the valves in the sump telling you what has to increase or cut back.. Its pretty much about understanding what you need to do to raise or lower the levels in the two chambers and in the tank. Common sense really just understand how much water you want in the sump with your pump off which makes it impossible to have an overflow in the sump.

 

[JMorris271]

Run it like a bean animal. Just plug one hole. One side is the full siphon and emergency drain. Other side is the plugged hole and the return pipe.
That's what I would do with duo overflows.
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I tried that out.
Most common problem with that setup is circulation of the stagnated water remaining in the overflow beneath the siphon drain.

 

[nereefpat]

Run it like a bean animal. Just plug one hole. One side is the full siphon and emergency drain. Other side is the plugged hole and the return pipe.

That's what I would do with duo overflows.


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That would be a Herbie, no?

Bean has full syphon, trickle, emergency drain.

 

[Capiross1]

Best Way to Set Up Dual Overflows

What if you did a herbie with full siphon and return in one over flow and emergency and 1 return in the other you might have to clean the emergency overflow box out via siphon a couple times a year


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[Capiross1]

Other option could be remove 1 overflow box which would free up some space plug those 2 holes and run you basic herbie with the return over the top, if it was mine that's what I'd do those boxes take up so much room


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[CStrickland]

I have a dual drain 120, I put a full siphon and return in one overflow and the other has a standard herbie. It's ok. It was hard to get tuned but if you use gate valves you can mess around until you have it right and it will stay there. The main issue is that the herbie uses a trickle drain to set the water level, you want it an inch or so below the weir. My trickle really works more like the emergency drain on a beananimal, flood protection, and the water levels are set by tuning the valves on the full siphon drains.

I think if I was going to do it again I might do a pair of herbies with the return over the back, but it's a close call. I think that would have been easier to get set up but now that mine is all tuned in I'm perfectly happy with it. It's quiet and I don't worry about floods. I also like how my screen top doesn't have to work around a return, it looks pretty slick all nice and flat.

They do collect stuff in the bottom of the overflow. If you use a bulkhead with a slip connection for your stand pipe you don't need to glue it you just jam it in there. Then every month or two you can put on a filter sock on the drains and lift out the whole standpipe. That drains the overflow quickly down the empty bulkhead, flushing the detritus into the sock.

 

[CarrieB]

Thanks all. The GMACreef. Com site is indeed very useful. That's the reference I used when we were plumbing the first tank. I just didn't find it very definitive on which was the best way to do a dual overflow, just offered options.

We are leaning towards Herbie on one side with a second drain and return pipe on the other.

In theory this violates the principle of having the emergency drain bigger than the full siphon capacity if you count both sides, but I think this would be okay as it seems really unlikely that both siphons would block at the same time and I'm not planning on running both at full capacity. More like splitting the work in half for each side, so that both overflows get circulation.


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[CStrickland]

Yeah, on mine I can close both drain valves all the way and the emergency can handle all of the flow. I think that in this setup it's more about the emergencys capacity relative to pump output, as opposed to the drains. If that makes sense. Like, no matter what configuration of clogs you could have, if the E drain can handle everything the pump sends, it won't flood no matter how many drains that is normally split into. I think it's just easier to explain it as a rule about drains when you are talking about setups that only have one drain, as in a standard herbie.