Overflow with dual U-tubes

[AdamHorton]

I recently bought a new overflow cup to replace one I had broken and this one came with two slightly smaller U-tubes instead of the single larger one I had before. I got them both set up and everything is working great, except that one of the U-tubes gradually gets more and more air inside it until it loses suction completely.

Could it be because the flow isn't enough that I need both tubes? It seems to be doing fine with just one tube...

 

[neilanh]

yeah that's exactly what it is. I have the same issue, one of the 2 tubes will collect air overtime because there's not enough flow to keep them both fully primed.

 

[cmor1701d]

Add a larger pump

 

[abdhalim2]

second on cmor...
add a larger pump or just remove the other tube...