So I picked up a few bulk heads from Neptune's, I got both of the sizes they had just to make sure I got the right one for my tank. I then went to HD and couldn't find any PVC piece that screw over the bulk head (red circle, 1" piece), however I did find pieces that will fit inside the bulk head (yellow circle, 3/4").
Since this is going to be for the return pump I wont have to worry about the size of plumbing going up to the return bulk head/flow nozzles correct?
Also has anyone used plumbers paste to help make a seal with the bulk heads, gaskets and the glass? The company that the internal overflow came from suggested it as was just curious.

Since this is going to be for the return pump I wont have to worry about the size of plumbing going up to the return bulk head/flow nozzles correct?
Also has anyone used plumbers paste to help make a seal with the bulk heads, gaskets and the glass? The company that the internal overflow came from suggested it as was just curious.