skimmer not skimming

[rusty shackleford]

your right, this is the first skimmer iv had.
the pump is as far up as it can be, theres a vinyl tube acting as a coupler to connect it to the inlet.

i posted a couple pictures earlyer and it looks to be functioning the same as it did when i first had it skimming correctly - same head hight and airflow

do you think its at all possible that leaching chemicals could have somthing to do with it ???