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

[jsodwi]

Always use the both siphon tubes. Also make sure whatever pump you will be using doesnt flow more than the overflow box will handle. So if your overflow box is rated at 1200gph, Make sure the pump isnt rated for that #. Overflow box always has to be more than pump. I ran a 950gph with a 1200gph overflow and a 30g sump on a 150g a few years back. Tank was heavily stocked and it worked like a dream

 

[tvanslooten]

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

Wow...great reply! Thanks. The inside diameter of the siphon tubes are just under 1 1/4". According to the chart, that means each tube has a flow rate of 937.5 - am I reading that correctly? If I am, then clearly one siphon tube will be plenty since the pump is rated at a maximum of 900 and with the 3-4' head it's only rated at around 700.

Travis

 

[tvanslooten]

Always use the both siphon tubes. Also make sure whatever pump you will be using doesnt flow more than the overflow box will handle. So if your overflow box is rated at 1200gph, Make sure the pump isnt rated for that #. Overflow box always has to be more than pump. I ran a 950gph with a 1200gph overflow and a 30g sump on a 150g a few years back. Tank was heavily stocked and it worked like a dream

Makes total sense...now I just have to figure out what the flow rate is of the overflow box. This thing has no paperwork so I have no idea. All I know is that it has 2 bulk heads/intakes going down to the drip tray. Each PVC pipe for the intakes is apprx. 1 1/4" in diameter...if that means anything.

 

[jsodwi]

From all the overflows that I have seen, the ones with the 2 tubes run from 1200-1500gph. With a 120g , If you ran somewhere around the 800-900 gph you should be fine

 

[duanes]

Make sure you have enough pumpage to fill both u tubes, if the pump does not push hard enough, siphon can break, because, air can build up in the arch. If this happens, its better to use one U tube that fills completely than 2 that have a wimpy flow.

 

[ruddybop]

Wow...great reply! Thanks. The inside diameter of the siphon tubes are just under 1 1/4". According to the chart, that means each tube has a flow rate of 937.5 - am I reading that correctly? If I am, then clearly one siphon tube will be plenty since the pump is rated at a maximum of 900 and with the 3-4' head it's only rated at around 700.

Travis

Use both tubes!!!!! That chart is for PVC overflows that go down farther in the tank and get more flow than an overflow box. My guess is that each tube will flow about 500 to 600 gallons. So using both tubes like (((jsodwi))) said will give you about 1200 Approximately. Try the pump you have and if your not happy with the flow get a bigger pump....

 

[tvanslooten]

Use both tubes!!!!! That chart is for PVC overflows that go down farther in the tank and get more flow than an overflow box. My guess is that each tube will flow about 500 to 600 gallons. So using both tubes like (((jsodwi))) said will give you about 1200 Approximately. Try the pump you have and if your not happy with the flow get a bigger pump....

Excellent...thanks. I'll be setting it up this weekend. I'll be sure to report back.

Travis


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[Crazyfish88]

If your buying a overflow box that comes with u-tubes and is designed properly then it should not break siphon. I've been using eshopps overflow boxes for 1.5 years on my tank and it has never broke siphon. Even when a power outage happens and when the power comes back on it still keeps its siphon. I would recommend any well designed u-tube overflow box over CPR's overflow or any other box that uses the unreliable tom's aqua lifter pump...


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