How Likely Is It The Siphon Will Break on an Overflow Box?

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tvanslooten

Feeder Fish
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Nov 20, 2005
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I am contemplating setting up a wet/dry on my 120 gallon tank. It's not drilled so I'll need to use an overflow box. I read on a website about wet/dry systems that the siphon on these overflow boxes "can" break sometimes - thus resulting in a flood of water on your floor.

How reliable is the siphon on these overflows? Is this something I should worry about or is there a very real possibility it could happen? I'm thinking once the siphon is running, it shouldn't break unless I disrupt it somehow, correct?

Travis
 
I think a lot depends on how you build your sump. Some guys build it that holds a lot of water in it. My sump it about 5 to 6 inches high were the pump is and it holds about 2 or 3 G of water in the last chamber. That's why it is important to have baffles in your sump so the whole sump doesn't get pumped to the tank. Only the last chamber in my sump will pump to the tank and not the whole sump. I have run my PVC overflow for over a year and never had to restart it.
 
ruddybop said:
I think a lot depends on how you build your sump. Some guys build it that holds a lot of water in it. My sump it about 5 to 6 inches high were the pump is and it holds about 2 or 3 G of water in the last chamber. That's why it is important to have baffles in your sump so the whole sump doesn't get pumped to the tank. Only the last chamber in my sump will pump to the tank and not the whole sump. I have run my PVC overflow for over a year and never had to restart it.
Click to expand...

This is a wet/dry system I bought several years ago. It's brand new and never used. I have no idea what brand it is or anything but it's definitely not home made. Looking at the system, there are no baffles or anything. It's wide open underneath the shelf that holds the bio balls. The sump area is 23" long by 12" wide - so the water trickles over the bio balls and goes into this area.

Even in your system you'd get some flooding (2-3 gallons of water worth), correct? But if you haven't had an issue for over a year, it sounds like I have nothing to worry about. I don't know anything about siphons and what breaks them but it just seems to me once you have them going they should never stop as long as you maintain proper water levels in the tank.

Travis
 
The sump itself has nothing to do with breaking siphon. Siphon is broken if air gets in the U tubes.
If bubbles get into the U tubes from weirs that are cut too low, or placed below outer overflow box level, and allow bubbles to build up in the upper arch of the tube. Siphon/tank overflow can be broken if debris builds up in the tubes and prevents flow. I check my U tubes daily, and make sure they are free from gunk and/or bubbles.
image001-65.jpg

A simple daily shake of the U tube will allow any build up to flow thru.
Unless your overflow is a CPR overflow you would need a luft pump, or to attach it to a power head venturi to insure siphon doesn't break. Below a CPR, it has never broken siphon while attached to the power head venturi port.
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tvanslooten said:
This is a wet/dry system I bought several years ago. It's brand new and never used. I have no idea what brand it is or anything but it's definitely not home made. Looking at the system, there are no baffles or anything. It's wide open underneath the shelf that holds the bio balls. The sump area is 23" long by 12" wide - so the water trickles over the bio balls and goes into this area.

Even in your system you'd get some flooding (2-3 gallons of water worth), correct? But if you haven't had an issue for over a year, it sounds like I have nothing to worry about. I don't know anything about siphons and what breaks them but it just seems to me once you have them going they should never stop as long as you maintain proper water levels in the tank.

Travis
Click to expand...

In my tank 2 to 3 gallons would not overflow the tank. It is a 220G with 2" from the top so I have a lot of room....

The thing to do is test it after you set it up. I shut the electricity off to see if my sump could handle the excess water from the overflow and it did. It filled the sump up without overflowing (1 to 2 " from the top). Then when you complete that test turn your pump back on and wait until the water levels off. Then pull your overflow tube or add air to your siphon to stop it and wait and see if the tank can handle the water from your sump.

It also depends on the size of tank you have. The larger the tank the more room you have if your siphon stops (For some unknown reason).

You don't wan't to buy a large sump for a small tank. Then yes you would overflow the tank if the siphon stopped. your measurements are 24x12 lets say it's 5" deep with water so that's 6 gallons of water you need to have room for in the top of your aquarium. Even that would fit in my tank because it is large surface area. My tank water level is 2" from the top 72x24x2 = 14 gallons of water my tank can handle from a sump if my siphon stops.

Figure out the dimensions of your tank after it is full and see how many gallons it will hold at your water level once you have set. Then figure out how high you have the water in your sump and calculate the gallons. Here is a auto calculator for rectangle dimensions to gallons. http://animal-world.com/encyclo/information/calculate.htm

You have a better chance of your electricity going out and not the siphon stopping...
 
It depends on how low you let the water in your tank get....if you keep the water level where it should be, and free of gunk it shouldnt stop.
 
Ive run a cpr and a regular overflow with u-tubes for about 4 years. As long as you set up the overflow right and make sure there are no air bubbles in it, you will be fine. After setting up test it out and shut pump off let it sit for a while then plug it back in. The overflow should remain working fine. If not you have air getting in somehow. Usually a small crack in the u-tube somewhere. I liked the CPR too but on occasion I had some debris get stuck in where the aqualifter pump plugs in therefore losing a good siphon. One suggestion I will make is hook up 2 overflow boxes. That way if one for some reason fails, there will still be one working preventing any possibility of flooding.
 
Looking at this unit further, I noticed it has 2 siphon tubes. The overflow box has 2 bulkheads/intakes going down to the sump as well. Am I supposed to use both siphon tubes or just one? If it came with 2, I'm thinking I should use both...but maybe not. I have no paperwork with this thing so who knows.

Thanks for all the other suggestions. I'm taking notes and will be employing a lot of this once I get this thing up and running.

Travis
 
tvanslooten said:
Looking at this unit further, I noticed it has 2 siphon tubes. The overflow box has 2 bulkheads/intakes going down to the sump as well. Am I supposed to use both siphon tubes or just one? If it came with 2, I'm thinking I should use both...but maybe not. I have no paperwork with this thing so who knows.

Thanks for all the other suggestions. I'm taking notes and will be employing a lot of this once I get this thing up and running.

Travis
Click to expand...

I would use Both...

Find out the Inside Diameter of the tube and here part of a stickey By Chompers on the aprox. flow of water. Then you can match/buy a pump that matches the overflow. Find out what one pipe flows and then you will know how much both will flow together. This is for a pvc overflow at maximum length. I think the Clear U piece overflows flow slightly slower. Thats why they have two U pieces to get more flow....(not Positive on that)

Maximum Gravitational Vertical Flow - This is what we look for when sizing drains or DIY overflows. The flow under the power of gravity reaches a maximum in the same way an object reaches Terminal Velocity as it falls through the air. The gravitational force is countered by the waters viscosity (resistance to flow) and the frictional resistance of the pipe. The viscosity creates a minimum vertical length to acheive the maximum flow. If the vertical pipe length is less than the minimum, the flow rate will be somewhat less than the pipes maximum potential.
size _GPM __GPH
1/2 = 2.50 = 150
3/4 = 5.63 = 337.5
1.0 = 10.0 = 600
1.25=15.6 = 937.5
1.5 = 22.5 = 1350
2.0 = 40.0 = 2400
 
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