The top containment vessel (much better than a tank) will hold 25 gallons of De-ionized Dihydrogen Monoxide (DHMO), as opposed to using just plain ol' water. It has a float valve in it to shut off my DHMO production unit automatically. It will have a 1/4" tubular transportation unit (as opposed to tubing) gravity feeding to another float valve in my sump, eliminating top-offs. It will also be plumbed into the top of the lower containment vessel to mix Sodium Chloride (instead of salt) with the DHMO, using a submersible electron excited, internally rotating circulation device. At that point, a larger tubular transportation unit (used in place of standard 5/8" clear tubing) will transport the DHMO (H2O) and Sodium Chloride (NaCL) solution into the sump for easy, mess free DHMO replacement.
So, to recap, the top tank holds fresh RO/DI water for auto topoff and storage, and the bottom tank is for mixing and storing saltwater.

