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Rogergolf66 06-05-2007 07:17 PM

Help please Overflow will not hold siphone?
Here are some pictures of my overflow It will not hold a siphone I don't know why. the concept design is the same as the one on my other tank and it holds a siphone. I siphone one of the tubes on the double overflow and it pulls all the water out of the black part that is in the tank and it losses siphone before I can even start trying to siphone the other tube.

Please help I don't want to have to buy a new overflow. I think I would drain the tank and drill it before buying another overflow, but I don't want to do that.

Here is the info when I bought it. notice it says it will not loose siphone if power goes out. I guess that is because it never gets siphone.

Brand New ESHOPPS PF-1200 Dual Overflow Box. 1,200 gallons per hour. Comes with everything you need to get it working.

Two U-Shaped Siphon Tubes

Two Sponge Pre Filters

Male & Female Adaptors - Bulkheads

Nylon Screws & Wingnuts

Pre Filter Box

Overflow Box

Dimensions: 10"L x 3.25"W x 10"H

Rated upto 300 Gallon Aquarium

Very Similar to the Lifereef overflows which sell for $199.00!

This overflow box has a great design, built with quality in mind.

Due to it's great design, it will not loose the siphon if your power goes out.

These are brand new and in their boxes!!!


SKAustin 06-05-2007 08:43 PM

Could be a design flaw. Could be faulty tube. Where does the air enter from that causes the syphon break?

Rogergolf66 06-05-2007 08:51 PM

the black box it never stopes siphoning and the black box empties.

I did try a old tube and it held a siphon but I only have one of them I need 2 also I want to use the tubes that came with it because the old tube is to long. the tubes that came with the unit are not the same length on both sides. the side to is in the black box is shorter then the side that hangs out of the tank into the overflow box out side ot the tank.


any ideas on how to get this to work?

SKAustin 06-06-2007 05:14 AM

Yep, sounds like a design flaw.

My suggestion, extend the pvc on the inner side of the bulkhead. have that extend about 1-2 inches above the shortest side of the U-tube

Rogergolf66 06-06-2007 05:32 AM

how. a coupling dosn't fit on it, and right now the shorter side is 1 3/4 shorter then the other side. It is with in the 1-2 inches you said.

Still lengthen and how?


usmc121581 06-06-2007 10:25 AM


Originally Posted by Rogergolf66
how. a coupling dosn't fit on it, and right now the shorter side is 1 3/4 shorter then the other side. It is with in the 1-2 inches you said.

Still lengthen and how?


I have the same kind and when I would loose flow after starting it is that the return pump wasnt pushing water up to the main tank from the sump as quick as the overflow could handle. Have you tried only doing one of the U-Tubes and then seeing if it will lose the siphon. I have a fealing that is what the problem is. That overflow can handle over 1200gal/hr of water flow. So if your pump is pusing out less its not enough water going into the box to keep the siphon. If you havent try using one U-Tube and see how it runs. Steve its not a design flaw. Those over flow boxes are very good. But I do see your point if the u-tube was built smaller, but I think the water flow isnt enough to keep it going.

Rogergolf66 06-06-2007 10:47 AM

ok well let me tell everyone exactly what I am doing maybe you can help this way. I turn the main pump on to push water up so it is above the overflow box. I then put an air line in the u-tube. then I put the u-tube in the overflow. I then suck on the air line pulling the water into the u-tube from the tank to the back of the overflow. this was all with one tube. It starts to siphon the water from the tank to the back of the overflow. Now at some point because the pump is not going it will run out of water in the black box to bring to the rear overflow.

Well here is what will normally happen. when the water stops flowing intothe box the u-tube will hold a siphon even thought the water it not flowing from back to front. THIS DOES NOT HAPPEN.

instead what happens is when the water stops flowing into the box the u-tube seams to take tomuch water out and it will not hold a siphon if the water is not flowing through. now Iunderstande the overflow will loss siphon if not enough water is flowing through it, but It should hold a siphon long enough to siphon the other tube and turn on the pump.
This all happens in about 3 seconds. no time to siphon the other u-tube or even turn on the pump.

Just so you know I did use 2 different u-tubes some old ones I had around that the U was the same size on both sides and it did hold a siphon. actually the overflow was not pulling enough water because after about 4 min. the pump was much faster then the overflow, and the water was about to really overflow over the tank onto the floor so I had to unplug the pump.

So I think this is all I know. what can I do?

Do I have to use the old tubes?

Do I have to add a ball valve on the return line of the pump so I can slow down how much water the pump is pumping into the main take so the overflow can keep up?

What do you recommend?

I just want to start the cycle on this tank and get the filters working to clear up this water. It has been sitting with only powerheads moving the water around the main display for about 6 days now no filtering.

usmc121581 06-06-2007 10:57 AM

Dont turn off the return pump. The u tubes will remove water quicker the you can return to start the 2nd. Keep the pump on when it gets to were you were letting it get to then begin removing and starting the siphon. Then do the same for the 2nd u tube.

jones57742 06-06-2007 01:24 PM


I am completely lost here
in physics you always get back to the basics.

The siphon will "pull water" until
1) the water level "drops below" the orifice of the "intake terminus" of the tube or
2) the water level "drops below" the orifice of the "outflow terminus" of the tube.


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