@Leebo - the below is no longer valid. I've rewritten it if you want to change it on the above link.
Original:
An optional Spool Piece (sold separately) is available to replace the cell during winterizing or cell maintenance. This will enable pool pump to circulate water with the cell out the of line.
New:
This applies to the Jandy AquaPure and the Nature2 FusionSoft as they are sister products. An optional "Spool" Piece (sold separately) used to be available to replace the cell during winterizing or cell maintenance. This piece has been discontinued and is no longer available. In addition, the AquaPure threads are proprietary and Jandy does not offer replacement proprietary unions (the "male" piece). If removing the cell is desired so that water may circulate without the cell, specialized plumbing would need to be added during installation of the cell. One method is an additional PVC union after each end of the cell. This method would require the purchase of 4 unions. 2 for when the cell is installed and 1/2 of the other 2 unions (the "male" 1/2) for creation of the bypass pipe.