broken skimmer?

My skimmer collection cup barely has any water collecting in it, and what it does collect is clear.  Now, I've got a decent amount of algae, so if my skimmer was working correctly wouldn't it be yucky(for lack of proper term) water in there??? 
I do 5 % water changes every 2 weeks and have carbon and phosphate remover bags in my back chamber.  My sand is full of algae and I keep manually pulling it out every other day. Pretty soon I'll be out of sand darn it!!  My rocks have some algae but it's mostly my sand.  Mostly slimy, red, guessing cyno.  But some looks almost hairlike and is brown.  My hermit crabs and snails don't seem to be doing anything to help.  
 
Could my skimmer be broken?? We've tried to fix it with no luck. We may order a new one. Also, was wondering about recommendations about getting a sandsifting goby or blennie that would fit in a 29 gallon biocube that would help keep the sand moving to see would that help??   
Thanks!!

 

I have an Oceanic Biocube Protein Skimmer. I've had it hooked up since March when I got my tank. I have a half a dozen corals, 2 clownfish, 1 firefish, 1 cleaner shrimp, and several snails/hermit crabs.

Thanks AJ!! I like your idea of trying new airstones first before we go out and get another skimmer. Do you or does anybody happen to know if they sell the replacement airstones anywhere in town for the oceanic biocube protein skimmer?? I was looking on the oceanic website and it didn't seem I could order from that site. I think I may have found some on www.fishsupply.com, but shipping is kinda expensive so thought if anyone knew of any locally in stores I'd check that out first.

I do have an extra powerhead so should have plenty of flow. I'll try new airstones, more frequent water changes, replacing phosphate/carbon again, I don't feel like I feed my fish too much. I only feed them one small pinch a day, how does that sound? For lighting..... 6:00AM blue lights come on, about 9AM white lights, then around 5:30 PM white lights go off and blue lights are on until about 10PM.

 

By blue lights I meant actinics. I keep my moonlights on 24/7. I'll try cutting back to 6 hours a day see if that helps. THanks again


Thanks Eric. Hearing they were around locally I tried Pet's Playhouse and they had the Lees brand you are talking about. I picked up a couple and have had one in overnight. I checked it this AM and there is already a little slimy, gunky stuff in there. Better than I was getting before!!!

Sorry, as you can see I'm not real good with the "technical terms", I really need Saltwater For Dummies!!! haha Thanks for the help.