I work at an lfs and we got the demo one in a couple of weeks ago...hagen trained me to use it...lmao
Anymoo...The guy said that as far as the carbon cartridge, the bottom just pops open, so all you have to do it open up the cartridge, pour out the old carbon, and replace it.
I'm not surehow often you have to change the pre filter, but it might be every couple of months or so once it clogs.
Overall I really like the filter. If I had 500 bucks laying around I would definantly get one, but alas, I'm just another poor college student...lol I've sold 2 so far since we got them in.