ATO return -siphon control- question???

ok...have a headache (blaming it on that) and can't think of a good idea on how to prevent a siphon. I've an auto-topoff system www.autotopoff.com connected to a 13gal tub.

1) First idea I had was to put a barbed T in the line with an elbow. Water just squirted out of the elbow even though it was as high as I could put w/out it squirting onto the floor.

Idea #2...put 3 small holes in the 1/2" tubing. Apparently not good either because water just came out of the holes :-/

--now i was doing these things to the hose inside the 13g.(trash can). Would it work better making little holes at the entry point into the sump? I just thought it's best where the hose is at it's highest point...coming out of the trash can.

 

Which way is it siphoning out? from your tank? or your ATO tank?

If it is from your tank than move the topoff line be out of the water line of the sump. Either way is a link to a check valve for 1/2"

Check Valve 1/2 MPT, Quest - $5.79

 

I have my ATO feed tube clamped down in my sump, but I have the tube's end sitting above the water line. That eliminates siphoning problems when the ATO pump turns off.

 

It's siphoning from the ATO into the sump. Ig'nant question here, but how's the check valve work? I clicked on your link, but I dont see how that'll work. Does it allow air into the line??

and Tigermike, I've the line entering the sump above the water line. My problem is not water siphoning out of the sump, it's siphoning out of the 13.g tub (ATO container

 

It's a one way valve,but if it does fail than you will have a problem. Since it's fresh clean water the chanses maybe be slim. Have you tried a t with a smaller 1/4 ro line pointed down in your top off drum?

 

got it squared away. cut off the hose w/the three holes and did away with the t-valve w/elbow. just did a single small hole further up the line...is just enough to break the siphon

thank you for your suggestions!