Skimmer issue

[Snappy]

I have a Aqua Medic turbo floater 5000 shorty that I just can't seem to get to skim enough. For example it would take 2 months or more at the present skim rate to fill the collection cup. I have 2 (1 in sump / 1 external) ocean runner 3500 pumps running it, have it turned all the way up to the max and still can't seem to get it to skim properly. I have heard good things about these skimmers but in my opinion it's a $900 piece of crap. I am at my wits end because it used to work well but hasn't performed in months and my tank is showing the results. What am I doing wrong?