I'm still waiting for the Canna Nutes (should be here this week) but the addition of the un-softened tap water has done the trick. A few days after adding it several fresh, spot-free green leaves started growing. The plants are now flourishing.

The water here measures 1250 ppm out of the tap and is loaded with Ca++ and Mg++. Nasty to drink though...

Thanks for the advice everyone!