Carboy Cap

[brackbrew]

Hey, I'm ordering a carboy cap for my 6.5 gallon fermenter for using my air pump and aeration stone, but don't know what size tubing I need. I bought a "universal" cap, but it doesn't fit the 6.5 gallon carboys I found out later (not very universal is it?!!!) Can anybody tell me, what size tubing I need for the holes in the top, obviously one hole will be for the airlock. The aeration system I'm using is the one sold on northerbrewer.com, if that helps.

Thanks, and as always,

BREW ON

 

[budbo]

Mine have 5/16th holes