Did you end up leaving a lot of slack on the stocking that you tucked into the tube? I made this mistake the first time, and the suction made something of seal out of the fabric, and all but stopped my filter flow. The stocking should slow it, but it shouldn't stop it alltogether. I would suggest cutting off some slack.
Now, if you went and did something silly like bought quality pantyhose, that could be the problem two; support hose and well made brands of pantyhose are very thick, so the water can't travel through with as great of ease. The best thing you could do is get a real dirt-cheap, ####ty, 50 cent pair from K-Mart and use those; they are super-thin, overly stretchy, and allow good water passage.
The final possibilty is algae. Does your tank have an issue with this ever? Algae looooves to build up on the pantyhose, so if you have algae in your tank, a good lot of it will build up and slow the intake. I had a tank that for whatever reason always seemed to have algae, even though none of my other tanks did, and its stocking allways got gummed up with Algae. It was worth the annoyance of cleaning it, though, to not come home to my betta plastered to the filter all pale with stress, his fins in tatters.