I just cleaned it with some vinegar and water. Here's a picture of all items included:
basic Elos NS 2000 skimmer with the original injector knob (seen in front of the skimmer in the picture below)
Eheim 1260 pump (original pump also has seen only 4 months of use)
optional injector cleaner (used instead of the original injector knob) hook up your ATO to this and you won't have to worry about cleaning it by hand periodically)