Anti-siphon tube losing siphon during outages

[pyro383]

Finished my sump setup and installed a anti-siphon overflow box. Tested out a mock power outage and after 2 min. the siphon tube loses its siphon.

I have a 45g tank and a 700gph overflow box. I bought the overflow box used so it is either a Amiracle or a Lifereef. The exterior box has the seperate chamber to hold water. Now the events that take place:

Shut off return pump, water level drops below the inner box teeth, water continues to be sucked through the J tube until almost 80% of the water inside the box is gone. Water stops entering the J tube and the exterior box stops also with the chamber being full. After 2 min or so the J tube loses its siphon, there is no apparent reason as no bubbles fill the tube.

Does the length of the J tube matter? Should i cut it down? As of now the tube inside the inner box is very close to the bottom of the box and the other end in the outside box is about .5" off the bottom. Looking at a few pics on the internet, the tube in the outer box is just below the partition ledge while mine goes to the bottom.

Hopefully this provides enough detail as I am desperate to prevent a flood.

[emelton]

Is the J tube the same length at both ends? If not try turning the tube around. Make sure he exterior box drain is higher than the bottom of the interior J tube but not higher than the drain slots. You also might have to adjust the interior box level. Hope this helps.

[lllosingit]

One thing to check.
Make sure the bottoms of the box's are at or near the same height inside and out side the tank, if they are not equal then the water will continue to drain until the water level is eqaul and that maybe enough to uncover one end of the U-tube.

[lllosingit]

Originally posted by pyro383


Does the length of the J tube matter? Should i cut it down? As of now the tube inside the inner box is very close to the bottom of the box and the other end in the outside box is about .5" off the bottom. Looking at a few pics on the internet, the tube in the outer box is just below the partition ledge while mine goes to the bottom.

Hopefully this provides enough detail as I am desperate to prevent a flood.
If you shorten the U-tube you'll probably make it worse.
Both ends of the U-tube should be submerged in an inch or so of water with the power off and if you shorten it to much will draw air and break siphon easier.

[pyro383]

I will have to cut the J tube since both ends are very much submerged.

[pmui]

is the tube in the outside box in the chamber that hold water? That chamber should be level at some point with the water in the tank when the power goes off.

[pyro383]

pmui, yes the tube is in the chamber that holds water. I will have to measure the water level in the boxes to see if they are level

[lllosingit]

Originally posted by pyro383
pmui, yes the tube is in the chamber that holds water. I will have to measure the water level in the boxes to see if they are level When you shut off the pump both sides of the box should hold enough water so that both ends of the tube are under water at least 3/4" or more.
The length of the tube doesn't matter as long as both ends stay underwater, the longer the better.

[pyro383]

well I trimmed the exterior tube length by about 1" and droped the internal box a bit more and it worked at keeping siphon. It just seems odd that the box sets the height of the water and not where I want the water to be. I wonder if the unit was made from different companies which resulted in differing measurements of the interior/exterior boxes

[zebrasoma17]

Eric:

I just checked my Lifereef box and it appears to be as we discussed. Water level in each box looks even when power is off. Also, the u-tube is the same length on both sides.

Al