Do you have a pic of what you built, it would be easier to troubleshoot.

good article found by another refer its posted not that long ago here http://www.aquaticplantcentral.com/f...ge-system.html

http://farm3.static.flickr.com/2530/...f005dab5_o.jpg

this will not work the way it is you need a hole where it goes over the tank also a check velve there. this design is poor will work with a couple changes. check out the links above thay have a design that works realy well.

Bill

best guess i could make would be that the air hole is too small. As stated it would be great if you can post a pic of the one you made.

Did you Prime it properly?

i have two overflows ..one with the air flow....one without
I like the one without the best....never had any problems...just use a pump that is rated a little higher

heres a pic
 

here are a couple pics of what i built.
for who ever asked if i primed it properly yes i did i filled all the chambers with water. anyways if you can help that would be great thanks everyone..

How are you going to start the siphon on that?

Looks good tho, interested to see how it works

I think you would need a 1" or 1.5" drain line to make something like this work properly. Yours appears to be 1/2" pipe, thus incapable of draining a significant amount of water. You may also need a gate valve rather than a ball valve for more accurate control.

Something like that should really be built out of clear pipe so you can monitor the accumulation of air bubbles see if it is primed properly. If you are on a budget, you could get away with having just one clear PVC pipe and the rest white.

the cap on the pipe that goes up comes off nothing is glued together yet.
and its 3/4" pipe not 1/2". and that ball valve was the only one i could find at the hardware store so thats what i went with. so ya i just dont understand why i get the syphon going and then it just stops..