because there is a slight space between the valve body and the extension (the height of the ribs on the VB) that isnt sealed (the ribs hild the extension up off the VB by about 1/16 to 1/8"), its could suck fluis in through that area, sown the second tube in the extension into the middle of the filter and then up the right tube in the extension into the VB.

if the gasket that was on there did not have the hole for the second tub, then that 2nd tube would be blocked by the gasket. as it is now, there is an opening however slight- and i dont like it