Help with Gravity ATO

[cindre2000]

I am having issues with a gravity ATO I am trying to build. The first attempt was with a standard issue 2.5g plastic jug from the LFS. I modified the cap with an O-ring to make it water tight and I drilled two holes towards the bottom of the jug and glued in two airline connectors. I then ran the two airline hoses into my tank.

The problem is that the jug continues to drain! I did some additional tests and found that both holes produce water and neither sucks up air, instead the jug just gets more and more empty until it reaches a critical threshhold and neither hole produces water.

I am thinking that I need to place one hole in the cap to allow only air in and the other low down on the side. Is my thinking correct?

 

[Anonymous]

The jug probably too flexible that it will drain for a while until it is deflated too much and won't drain anymore.

 

[ChrisRD]

I've never built one myself, but I think you're right in that the air draw line would have to connect somewhere near the top (or you'd need some type of "standpipe" inside the container connecting to the air hole you've already drilled at the bottom).

The original nurce units worked with the lines in the top of the container (one syphon draw and one air inlet) but the concept should be the same. Maybe a pic of the unit will give you some ideas:
http://www.aqualan.com/

HTH

 

[Entacmaea]

Hey there, I've built several of these and use them exclusively for top-off, and yes, ChrisRD is right- attach an airline to the lid and run it down to your sump- the end of the air line will determine the water level of your sump. Also, the walls of the reservoir (your jug) need to be rigid for best results. An old 10 gallon glass tank with an acrylic lid siliconed in place works well for these...

Thanks, Peter