[GenGoku]

you mean have the cap of the T straight up? if so, that's how it will be. When i move the T-cap straight up, in the basin, the waterflow doesnt seem to be much stronger. i just edited my first post to show how it will look in the case.

please correct me if i'm wrong.

[edit]
i thought it could be air trapped in the core or eheim, but doubt it as i've already tried moving it around as much as i could--don't see any more air bubbles flowing out of it when moving it.

[edit2]
oh my gosh. i might have another doa core. i tried finding the bottle neck by testing the eheim by itself then with the eheim + core. i put the core outside of the basin so it's out in the air. i can shake water out the core.

[edit3]
yep. i think it is. this one is even worst than the last. i had to try a little hard to get some water to come out of the last core, but this one, i just shake it (by itself, filled with water, thumbs plugging barbs) and a whole lot of sprinkles come out.

i really hope i'm wrong and it's just water that accumulated while it was in the basin. i'll try again in the morning after the exterior has had time to dry out (leaving water inside) and do my "shake test" again.