Aquarium pumps getting clogged.?

Ok I have two filters on my tank a biowheel and canister. On top of that i have a current pump and a skimmer. The pumps for the skimmer and current are getting clogged. The skimmer has a foam sleeve around it and the current pump has nothing. The current pump still works though it could stand to be cleaned. But the skimmer yet again isnt working and the foam sleeve is crumpled up as if its clogged(not a lot of water flow through the pipe anymore either). Now my question is can do without this foam sleeve that continually gets clogged or is there a better thing i can use to fix this problem. Please let me know your thoughts.