depends on what you have. there are older canister style filters that have an element on the inside. there are also water separator filters that look like oil filters.

if yours doesn't look like this:

i'd recommend switching to it. yes, skidim is one of the places you can get it. the filters for the older style are hard to find and will only get more difficult. not to mention the older ones are harder to change, the one i showed just spins on and off like an oil filter.