# Full Siphion Overflow



## KaiserSousay (Nov 2, 2008)

OK, here we go again..I think this might work








The idea being a completley quiet pvc overflow that will automaticly stop and start with the pump.
At Power Off-water level drops to the siphion break hole, the height of which you determine by the capacity of your sump, and your flow stops.
At Power On- pump starts, water level goes up in the tank, at the same time a suction is started either by an aqua lifter pump or,in the case of my pump(CA1800)one of the 3 venturi by way of air line tubing from pump to fitting on pipe going to the sump. This should start a full siphion with no noise whatsoever.
So..have I completly lost it, or am I on to something here?


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## zacw240 (Oct 28, 2008)

I haven't built a PVC overflow yet but have been researching the **** out of it, and in my opinion i don't see that working to its full capacity. I think the location of your suction fitting should be atop your u tube to take out all the air because that's what most peoples complaint is with these units. There not working at a full flow due to trapped air at the top.


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## Jakemonaghan90 (Nov 30, 2008)

This looks like a good idea to me.

Being that this has no vent and the intake will be fully submerged when the pump is on, the venturi will suck all of the air out no matter where it is placed.

Once all of the air is out, no ifs and or buts about it, you will have a full siphon.

Ahhh, noiseless bliss!

Just make sure 1 inch PVC at FULL siphon (850 gph???) wont out do your pump.

DO IT NOW!!!!!!!!!!!


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## CICHnes (Jan 30, 2009)

Have you tried it yet. I don't know if an aqualifter has that much ooomph to suck up the water after a power outtage. I think it might overflow before it does. Keep us updated, I hope it works.


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## KaiserSousay (Nov 2, 2008)

I tell ya, can`t wait for the weekend to give this the "garage try out"


> suck up the water after a power outtage


Thats the BIG test..not even going to try the aqua lifter, if the venturi on my pump won`t do it, neither will the aqua lifter. With 3 venturi available to me, might end up having more than a single suction fitting on the pipe. Hope it would go with just the 1.
Was thinking that this might not work on a traditional wet/dry..with no water in the pipe at start up. Might need the pipes end in a vessal to hold some water in the pipe at start.


> 1 inch PVC at FULL siphon


I used that size for no other reason than I have a bunch of it from other projects..can always valve down the flow.


> Keep us updated


Ya`ll will be the second to know


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## RyanR (Apr 29, 2008)

I just don't see it working... at power off, it'll siphon down to the "siphon break", at which point the the whole system will be empty. You'll need an intake from a jet engine to draw water back up into the overflow, since the sump end will be wide open, and the path of least resistance will be for the venturi to just suck air.... or is the other end submerged in the sump?

This is why overflows have two "loops" open to the air... that's the only way to keep the prime.

-Ryan


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## CICHnes (Jan 30, 2009)

This is the design that most PVC overflows look like, this one is the one I built just recently. 1.5 in PVC minimized to a 1 in to the sump.

Front (inside tank)










Top










Back (to the sump)


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## CICHnes (Jan 30, 2009)

This is the design that most PVC overflows look like, this one is the one I built just recently. 1.5 in PVC minimized to a 1 in to the sump.

Front (inside tank)










Top










Back (to the sump)


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## bulldogg7 (Mar 3, 2003)

I think the biggest problem would be the flow rate balancing act. If the pump was slower the siphon break would stop the sump from flooding but it would be a big flush/gurgle every few minutes as the air entered and reprimed. If the pump was faster, it would either flood the tank or suck air in the sump making even more noise.


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## RyanR (Apr 29, 2008)

bulldogg7 said:


> I think the biggest problem would be the flow rate balancing act. If the pump was slower the siphon break would stop the sump from flooding but it would be a big flush/gurgle every few minutes as the air entered and reprimed. If the pump was faster, it would either flood the tank or suck air in the sump making even more noise.


Totally true.... plus the flow is never constant. As the sump water evaporates, the flow rate of the pump will lessen since there's more "head" to pump against.... not a significant amount, but this is why the overflow has to be 100% passive and not valved, with the flow rate entirely driven entirely by that of the return flow from the sump.

Also, the airline nipple needs to be at the highest point in the system.

-Ryan


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## imusuallyuseless (Dec 28, 2005)

bulldogg7 said:


> I think the biggest problem would be the flow rate balancing act.


Exactly :thumb:


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## KaiserSousay (Nov 2, 2008)

Seems to me, bulldog got told his skimmerless overflow would not work, or did I misread :-? 
If it doesn`t work all I`ve lost is some time and a few fittings....But....
If I can get this off :thumb: 
BTW..I do know what a regular pvc pretzle looks like, honest I do  
As to placement of the suction fitting being at the top of the "U" well, when you start your siphion at water change time, where do you suck, at the top of your tubing :roll: 
Any how, got ya`ll interested eh.
Hoping to give ya good news by monday, but if not, thats ok too.


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## bulldogg7 (Mar 3, 2003)

I got told plenty of time it'd never work  Made me want to try it more. I think the airline placement should work as long as both ends of the drain are in the water, it will be harder to pull the water from the sump, so you'll just need to pull the water up through the U-tube and get it started flowing. It might bubble back up, that's where having the airline near the top might help. 
opcorn:

With the pretzel you could just add another couple of 90's to the end and have it sucking from the bottom, seems it would be pretty quiet, but I haven't tried it yet.


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## KaiserSousay (Nov 2, 2008)

quiet it wasn`t, got it so I hardly noticed it..but the other half..cold fire dripping from her eyes and the words "will it ALWAYS make THAT noise" still send a shiver up whats left of my spine 
I`ll see what develops weekend wise, might be back monday sadder, but mos def wiser, or?


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## bulldogg7 (Mar 3, 2003)

Sorta what I was thinking about, just adding a couple of elbows to CICHnes' design


But I wanna see if your siphon is gonna work.


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## boredatwork (Sep 14, 2007)

I'm torn here. My first impression was "Nope, this won't work." Then I thought about it for a while and decided, "Wait, of course it will work." Then I got thoroughly confused. But I was able to fight my way back to sensibility, and have decided to wager on "Who knows!?".

But I am leaning toward, "It might work, but not how you think." As already mentioned I think you will get the toilet flush effect because of unbalanced flow rates.

This is what I think will happen. First lets throw out some numbers. Assuming the GPH of your pump is less than the assumed max flow rate of a full siphon, lets say you have a 500GPH return pump. The assumed max flow rate of a full siphon is 800GPH. Now, lets go through a mental trial run.

0. Overflow and drain pipe are full of air, one end is submerged in the tank and one end is submerged in the sump. 
Venturi from sump pump is connected to drain pipe.
1. Turn on pump. 
2. Water is pumping into the tank at a rate of 500GPH.
Venturi is sucking air out of drainpipe, but siphon break is exposed, so nothing happens.
3. Water level covers siphon break
4. Venturi start sucking air out the drainpipe causing negative pressure.
Water level in tank is rising at a rate of 500GPH.
5. Negative pressure building up inside the drain pipe causes water from tank to be sucked into drainpipe
6. Water is sucked through drain pipe and starts falling over the U then down into the sump, eventually at a rate of 800GPH
7. Siphon drains water at 800GPH which is quicker than pump return of 500GPH, so siphon break will eventually be exposed and siphon will break.
8. Go to step 2.

The danger here is in the time to create the siphon. One of the bad things about the toilet flush phenomena is that if the time to create the siphon is greater than the time to overflow your tank - well, that would not be a good thing.

And now for something completely different.

I think some people are familiar with the Herbie method. I still stand by my claim that it is the only way to have a silent (and working) sump design. The method proposed here is essentially the Herbie method without the gate valve. The only difference is in how the siphon is started. In the Herbie method gravity starts the siphon, here a venturi starts the siphon. It is a known fact that the Herbie method depends on precise tuning of the gate value. In other words, the Herbie method does not work (at least not quietly) without the gate value. So now I am definitely leaning toward "It might work, but not as expected."

So I still think the Herbie method is the only way to do it. But of course I am usually wrong so I guess we will just have to wait and see!


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## boredatwork (Sep 14, 2007)

bulldogg7 said:


> Sorta what I was thinking about, just adding a couple of elbows to CICHnes' design
> 
> 
> But I wanna see if your siphon is gonna work.


This kind of design will never be quiet no matter how many twists and turns you put in it. Unless you either have no drop to the sump (which is impossible) or your flow rate is ridiculously low (which usually defeats the point of the sump). But in principle it can never be quiet.


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## KaiserSousay (Nov 2, 2008)

Nevermind  
Couldn`t wait..tried a number of different configs, all for naught..
I guess sometimes you just have to obey some laws of physics, damm it.
Now I`ll go back and mop the garage floor :lol:


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## JALOOS (Sep 6, 2008)

Aside from the intial cost I am very happy with the overflow box that I purchased when I set up my tank. It has two 1 inch drains and does a fine job. There was some noise issue at first but I have cured that by coring out a large foamy (from another filter) so it sits over the stand pipes, on top of this I use about 4 to 5 layers of filter floss. This not only keeps down the gurgling sound but provides extra mechanical filtration and keeps the extra crud out of my sump. A great place for the colonization of bacteria as well. I have been able to keep my filter floss in the sump for up to 6 months without clogging. I replace the floss once a week with the Wallmart floss and everything is good. If your looking for extra mechanical filtering then this is the cats ass. On my drilled out overflows I fill them with bio balls leaving room for layers of floss on top as well great way to add extra filtration and keep sumps clean. If the other half is concerned about the noise and giving you grief over it might be worth the investment of an overflow box.


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## RyanR (Apr 29, 2008)

The problem is that you can never have a "siphon break" in the conduit of water that goes up over the edge of the tank. Any system that lets air in there when it loses power simply won't work: It'll lose its "prime" and you'll flood the room when the pump starts up again.

This is why the HOB part must be shaped like a "W", with the two outermost "tops" of the "W" open to the atmosphere.

-Ryan


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## KaiserSousay (Nov 2, 2008)

RyanR said:


> The problem is that you can never have a "siphon break" in the conduit of water that goes up over the edge of the tank. Any system that lets air in there when it loses power simply won't work: It'll lose its "prime" and you'll flood the room when the pump starts up again.
> 
> This is why the HOB part must be shaped like a "W", with the two outermost "tops" of the "W" open to the atmosphere.
> 
> -Ryan


Yeah Bubba, but it stopped and started just fine...OK :thumb:
No Mas por favor..This was never intended to have all the short commings of ALL pvc pretzel overflows, already been there, done that.
Neither vessal, tank or sump, ever came close to overflow. 
The problem was the surge as sump and tank tried to stay in balance with the pumps flow.
Started to try some adjustments..but then that was exactly what I was runnig from, not just the varying amount of gurgle, whoosh, etc., but the adjusting hassle at stops-starts.
Oh yeah, all told ya so`s will just be written off as "them that can, do..them that can`t....."
I think ya get me drift, eh. 8) 
Did work out a super easy set up for future projects, stool and 2 5gal buckets..even broke out the old hob overflow and patched together bulldogs set up and ran it for a while,,,worked, just as he said it would. :thumb:


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## boredatwork (Sep 14, 2007)

Since you have a "super easy setup" you can try a valve in the return pipe to the sump. It will allow you to match the sump return flow rate and the drain flow rate.


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## boredatwork (Sep 14, 2007)

JALOOS said:


> Aside from the intial cost I am very happy with the overflow box that I purchased when I set up my tank. It has two 1 inch drains and does a fine job. There was some noise issue at first but I have cured that by coring out a large foamy (from another filter) so it sits over the stand pipes, on top of this I use about 4 to 5 layers of filter floss. This not only keeps down the gurgling sound but provides extra mechanical filtration and keeps the extra crud out of my sump. A great place for the colonization of bacteria as well. I have been able to keep my filter floss in the sump for up to 6 months without clogging. I replace the floss once a week with the Wallmart floss and everything is good. If your looking for extra mechanical filtering then this is the cats ass. On my drilled out overflows I fill them with bio balls leaving room for layers of floss on top as well great way to add extra filtration and keep sumps clean. If the other half is concerned about the noise and giving you grief over it might be worth the investment of an overflow box.


A foam insert into the stand pipe only muffles the noise. With any over the tank overflow you are going to have noise. You may be able to quiet it to some extent, but you will always have noise. This is why drilled tanks are preferred.

I only mention that because so many people seem to think there is not advantage to a drilled tank. If you do a search on overflows you will find that a drilled tank gives you far superior options when it comes to a quiet sump setup.

I really think that is a necessary point to really drive home. If I had understood the importance of that when I got my tank I would have gotten it drilled. But at the time I didn't know what I was doing and I was influenced by the many posts of people saying "over the tank overflows are really great!" I really regret that and now out of spite and with a helpful heart I try hard to make that point very clear.


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## KaiserSousay (Nov 2, 2008)

> try a valve in the return pipe to the sump


Thanx BAW..


> Started to try some adjustments


That was where I started....
Gave it about an hour..then gave up on it.
No matter the amount of surge, nor length of time between surge, the flaw would still be there.
Will just file this away and still think on getting drilled performance on an undrilled tank. For those of us with more time than money, tempered tanks,lust for sumps..well, any how..have not just givin up on the goal.


> over the tank overflows are really great


In my case, sumps are great, the overflow is an evil needed to use it.


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## boredatwork (Sep 14, 2007)

KaiserSousay said:


> In my case, sumps are great, the overflow is an evil needed to use it.


That's a great way of looking at it. I couldn't agree more.


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## parkayandbutter (Jan 15, 2008)

Here is a simple purchase for you: http://cgi.ebay.com/Aquarium-Overflow-B ... 1|294%3A50


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## boredatwork (Sep 14, 2007)

parkayandbutter said:


> Here is a simple purchase for you: http://cgi.ebay.com/Aquarium-Overflow-B ... 1|294%3A50


I wouldn't use that as an alternative even if it was free. First, the reason most people go to an over the back type overflow is not because they didn't think about drilling their tank, but because they don't want to drill their tank.

Second, aside from drilling the tank, this is the worst kind of overflow because its the worst of both worlds. From the ebay description:



> QUIETLY drain approx up to 800GPH. DID I SAY..... quietly? This is because the water draining down has the ability to mix in air with it.


This kind of drain will not do much better than the commonly quoted 650GPH for a 1" pipe. You only get the 800GPH from a 1" pipe if you have a full siphon- which means no air. Related to that is the fact that this kind of drain is absolutely 100% NOT quiet. And the very reason it will be noisy is the reason it states it is quiet. It will be loud, not quiet, because air is sucked in through the vent. No one should ever buy this.

If you are going to have the noise, you might as well just use a regular over the back overflow and avoid the grief of drilling your tank.


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## CICHnes (Jan 30, 2009)

If you're heart is set on not drilling the tank, the CPR Overflow is the way to go. I have the CS90 and CS100, and you don't hear them at all.

www.cpraquatics.com


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## KaiserSousay (Nov 2, 2008)

CICHnes said:


> If you're heart is set on not drilling the tank, the CPR Overflow is the way to go. I have the CS90 and CS100, and you don't hear them at all.
> 
> www.cpraquatics.com


Thanx..I looked at that, saw a pretty mixed bag of reviews on the SW/reef sites. Add to that being a surface skimming overflow was the deal breaker for me.
I agree with bulldog, the bad stuff is hardly ever floating, it`s down, towards the bottom of the tank. That is where my lift tubes need to be. 
On my eheims I made lift tubes that pull from the bottom and from 3/4 up, seem to be working fine.
On drilling, my heart would would not be the only thing to break..tempered glass walls  
I`ll keep running the canisters, but will still try various things that pop in my tiny, little head.


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## One_Cich_Dude (Feb 2, 2009)

Powerhead venturi?

Just curious, which brands and sizes of powerhead are you guys using that can prime an overflow using teir venturi? I tried 3 different powerheads and none of them had enough suction at their venturi port to start a siphon in a PVC overflow.

What might work is putting a python venturi on the return line. I have everything I need to do this except for an adapter from national pipe threads to garden hose threads that the venturi requires. Problem is, the only adapter I have found is solid brass, a no-go for aquarium use.

I know the python venturi has enough suction to prime an overflow.


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## JALOOS (Sep 6, 2008)

One_Cich_Dude said:


> Powerhead venturi?
> 
> What might work is putting a python venturi on the return line. I have everything I need to do this except for an adapter from national pipe threads to garden hose threads that the venturi requires. Problem is, the only adapter I have found is solid brass, a no-go for aquarium use.
> 
> I know the python venturi has enough suction to prime an overflow.


Try this










http://www.kentmarine.com/products/venturi-valves.htm

Already has pipe threads on it. Nice to see they are black the few I have kicking around are white.

For what its worth I have an overflow box and it can be primed by a crappy Odyssea ex-100

:thumb:


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## One_Cich_Dude (Feb 2, 2009)

JALOOS said:


> One_Cich_Dude said:
> 
> 
> > Powerhead venturi?
> ...


Wow, thanks for the link. That's just what I had in mind, only with about 5 less parts to get it to work!

I still don't understand why I have had no success using powerheads to prime my overflow.


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## JALOOS (Sep 6, 2008)

One_Cich_Dude said:


> JALOOS said:
> 
> 
> > Wow, thanks for the link. That's just what I had in mind, only with about 5 less parts to get it to work!
> ...


I have noticed that the powerheads have to be near the surface of the tank to be able to draw the air out. The lower in the water the powerhead the harder it is to suck the air down that far. Try it at the water surface level. Keep the hose length as short as possible.


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