Just a warning...I've changed the water once in my Optima, and at that time thought I would just rinse out the disposable filter a little, since I am hoping to get at least 8 months out of it.
Well, it looked as if it started to come apart by the water pressure, so I stopped.
I would suggest you get one of the $60 washable filters that can take the place of the throwaway, just for the time period you want to flush out the foam away stuff.
I have one as a spare, just in case my dealer doesn't have the disposable filter in stock when I will need it, or if something major happens were I need to do multiple rinses.