Hydrokinetix Heating System

Recently bought a house with a hyrdokinetix heating system, which
utilizes a water storage tank it heats at night during off-peak hours
for hot water to heat up the coils in the blower. There is also a
heat/AC heat pump outside. I assume one of these is the primary and
the other the secondary heating system.

What type of regular maintenance needs to be performed on the
hydrokinetix tank? I am guessing a metal tank could rust, so should I
use some sort of rust inhibitor?

Information on these systems seems hard to find, so any comments or
tips are appreciated.