hello, I have a recently installed (January 2016) Aqualink PDA-PS4 (on a 24K gallon pool/spa combo). What exactly do I need to add an Aquapure PLC1400 and have an interface between the two?

Do I need the standalone Power center or do I need to replace the existing Aqualink power center with the "Zodiac 6613AP PureLink Standard Power Center with Salt Water Chlorinator"?
- minimum I want to turn the cell off when I put the Aqualink in SPA mode
- salt readings on the Aquapure would be "nice"
-any other advantages with integration?