We have had the AR-400 for a week, and ordered the ozonator separate.  My fiance installed the ozonator himself and said it was not very hard to install as everything is marked inside the control panel on where to connect the ozonator.  We are also using Nature2Spa mineral stick, which took us a while to figure out how to install because it seemed too easy.  But it was that easy, just insert the mineral stick into the middle of the filter holder.  You have to push down on the hinged lid and drop it in, too easy!