Whether the hole is too big or the carto too small or the O rings are too narrow...it all boils down to a failure in design.
If the tanks were designed to be used only with certain diameter cartos, or only certain brand cartos, that shoukd be stated in the product description. I have dozens of boxes of cartos. I am not going to jettison them all (I have more than one brand) to accommodate a single tank that requires a specific type. It works good when and if it works, but it's too fiddly and flawed for mainstream, imo. A design overhaul is in order. It was a great idea. Just inconsistent execution.
QC isn't so great with them either. One of my bottom pieces didn't even have the slots on it. The surface was totally smooth. Duh. No airy no vapey!