well no, if u have the acrylic baffles removed, and the connector plug removed so both res's are tied, as well as right fill port sealed, left seal port open, what happens martin is you get a massive vortex in the right side.
eventually all that air is either pulled though the inlet or shoved though the internal hole to the left side.

This is why u only need to top off the left side, because eventually the right side will be completely purged.