What if you put your pump in your res and fill your system that way. Do it long enough to make sure all the bubbles are out, then put the hose on the inlet barb of your pump UNDER the water. No air- no need for an air trap, right?
This does work. I have mine in this setup right now, but you can still get air in the other parts of your system. I have my heater core mounted at the very top of my computer and when I've filled/charged my water cooling setup, I normally tilt the system around after I think all the bubbles are out. I always get a couple more air bubbles that were stuck in the heater core.
i also for the time being do not have a T or res. i just tried to get all air out of core and block and slipped on fitting underwater as mentioned. no big bubbles (that i've noticed) after about a week or so. I want a T line though - would be easier
t lines are real easy to make i really dont see any reason not to have one