The end facing up is also too small for the thread? I can slide it in and out easily? I have sent an email to The Reef Shop so lets see if I can be supplied the correct partThe end facing up is the side that goes into the filter. Thread tape the crap out of it and it should be water tight. The left side is the hose outlet connection end, and the threaded hole in the tee is for the pressure gauge.
:D
I wrote the OUT on it lol, i have since realised its wrong, need to get some turps on it!Looking at the fitting it should be going on the "in" side of the filter housing not the out side as your photo shows.. Also rocker is right about the gauge going on first don't make the same mistake I made. :)