yeah, at first i thought the inlet barb was huge compared to the 1/2" clearflex60 ID from cooltech. it takes a little massaging, but it'll fit. you don't need to buy a replacement.
after getting a small piece of the barb in the tube, the trick to get the rest of it in (from what i learned) is to push in with the tube then and to one side. continue to do this from one side to the other.
[edit]
ok. i guess explaining it with words isn't my forte, but these videos should help
attaching (i didn't put it all the way in, but you get the idea)
removing
(quality ain't that great since i used my webcam to make em. you'll also need divx codec to view them)
here's a pic of the attached hose
check out
my thread about the eheim barb sizes.