Help with overflowing sump system
 

I have a 40g breeder connected to a baffled 20g sump but I am having a lot of troubles with it overflowing completely after the return pump is shut off which causes a big problem as power outages are frequent.

There are many aspects that causes the overflowing of the sump and ill try my best to break it down

Mainly what happens is when the return pump is turned off, water will flow down into to overflow box and into the sump, but once that stops water will be sucked in from the return pump nozzle that usually pumps out water, but instead it creates a siphon sucking down water into the sump. I cannot move it or unscrew it from my tank which will position it in line with the water, and I also cant unscrew the PVC u turn that has been glued together with some kind of epoxy.
This is my tank :
http://i.imgur.com/1Lyyll0.jpg


This is my sump, the left side is the return pump and the right side is where the overflow box leads to
http://i.imgur.com/WjjLfBe.png

This is my overflow box, works great and when pump is shut off, it only drains water to a certain level and then stops
http://prntscr.com/95visu

As you can see in this image, this is what the return pump connects too. #3 labeled is stuck to #2 and since its stuck together, it is impossible to screw it out from the tank as #2 will be blocked by the glass on the left side. #1, the black nozzle can be unscrewed but does not fix the problem.
http://i.imgur.com/27SbZUC.jpg


This is a huge problem for me because if there was a power outage the water would overflow, and any help, solutions to this would be appreciated as I am out of ideas of what to do. If more information is needed or images I am more than happy to provide them

Many thanks

Twist the black loc-line pipe so the output is closer to the surface and/or drill a 1/8" hole in the plumbing somewhere to cause a siphon break (though I don't really see a spot that would help you out). If the black pipe is too short, add more to it. The output should be as close to the surface as possible without causing splashes or a vortex. This will minimize the back siphoning.

lift the return line u closer to the surface to suck in air and break the syphon on a power outage

edit: you hit reply, you go pull out dinner and you get beaten to the answer

You could also put a flap checkvalve right on the output of the pump. The weight of the water in the return line will shut the valve when the water stops preventing the back siphon. I know alot of people don't use them but I put them in all my systems and have yet to have one fail. Combine that with a siphon break hole up top and you should be pretty safe all round.

Thanks for the response, Since the white PVC has to be twisted so it's facing right due to leaking if it is not tight enough, I cannot angle the black loc-line pipe into a position where it is not splashing water onto my light and also does not create a siphon. About the drilling of a hole to stop the siphon where would I drill on about? Also where could I purchase more of the black pipe, or a split system that I have seen people use to disperse the flow of the return pump

Thanks

Thank you, that seems like a easy fix for the problem, however the large plastic tube I use that connects the pump to the tank itself is very short, would you recommend be boosting the return pump with a piece of plastic or get a longer tubing to create a U shaped bend to stop the siphon?

Thanks

Did a quick search and I think a flap checkvalve looks very efficient. Do you know where I could get one specific to my size of tubing? I will measure the diameter tomorrow. Also I dont have lots of supplies for plumbing so what needed pieces do I have to purchase before installing the valve? also where would I drill the hole and how big would it be?

Many thanks to the helpful replies

You have misunderstood what myka and I are saying.
The black plastic thats the output of the pump just aim a little bit higher say 1/2 inch under water so when power goes out and creates a siphon as soon as the black loc line #1 is out of the water it will break the siphon stopping flow.

My flap valve fails all the time the best solution is to lift the black return pipe as close to the surface as you can , you can also snap on some more links to make It longer , also you don't need it completely out of the water just right at the surface , when the pump stops running the water will drain a bit lower the level and breaking the siphon

Thanks everyone , I tried raising the black pipe to the point where it breaks the siphon but water is still slowly going down so It seems like it is leaking so I would need to get more black pipe pieces


Does anyone know where I can purchase more of them and also a more specific name other then black pipes?

Thanks