Siphon and Bubbles from Above the Tank ATS

[Spartacus66]

I have an SM100 style clone that sits above the tank. I have a pump in the display tank deliver water up and out, and then a 2" bulkhead (1" pipe) as the return back into the tank. There are three 90 deg turns that pipe makes, and I have a 1" to 3/4" coupling at the end to slow down the return water. My problem is when I have the flow turned down so the water level in the scrubber is right, I get a siphon forming at the drain that is loud and causes millions of bubbles in the tank, which is ugly and causes outrageous creep. So I have to turn up the flow which elimates the vortex in the drain, but also causes the water level in the scrubber to be pretty high. How can I have lower flow but avoid the gurgle, the vortex, the siphon the bubbles and all that? I don't understand water flow enough to figure out what I can do. The follow up post will have some pics of the setup. Thanks all!

[Spartacus66]

Pics!
http://tapatalk.com/mu/6c663cc7-91b3-bc52.jpghttp://tapatalk.com/mu/6c663cc7-91c9-d133.jpghttp://tapatalk.com/mu/6c663cc7-91e3-2b03.jpg

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[SantaMonica]

I think that the best way is never to let any pipe to horizontal, like the middle section of yours is doing. I think that using several 45 elbows, instead of 90's, will always cause a down slope to the water, which will always allow an up-path for the air.

Not totally sure about this, but it has stopped all gurgling in both of mine.

[kerry]

Its a drain just like for the toilet drain or any other waste drain plumbing. It just needs a vent like the one on your roof of your house, I run all my smaller drains with a vent or without on huge 2" pipe on a 45 degree angle so water is not consuming the entire circumference of the drain pipe and causing suction by gravity.

[Spartacus66]

Thanks for the responses! I'm not sure about making a vent; I just don't quite see how to do it. But I may try the 45 deg thing. That is relatively easy.

But if I did try a vent, how would I do it?

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[kerry]

this is the best image I can find for a vent, the vent pipe should be a high as the tank fill level to be safe. Here is the link. http://sinkholes1.com/island-sink-vent . The bent or dip in the drain pipe does not have to be there for an aquarium.

[kotlec]

A lot of good ideas can be found here :
http://www.beananimal.com/projects/silent-and-fail-safe-aquarium-overflow-system.aspx