Deep, if you are using borax to raise the pH (though raising pH usually isn't a problem with SWCGs), I believe that borates inhibit rust. Waterbear is conducting an experiment concerning borates and pH stability in SWCGs - it's http://www.poolforum.com/pf2/showthread.php?t=4712 - I'll try to get him and PatL34 to look at this to see if either of them can help.
I can't believe that the WAF is low, the salt water should feel like liquid silk and her hair should feel like she just conditioned it when she gets out of the pool (or, is she bald? ). Let me go see if I can get those guys to take a look here when they have the time