How many tanks are you running? I would think at least two, one with softened water for washing and one with RO (spot free water) for your final rinse.
When your gently rub your finger over a white spot, does it smear, wipe off, or stay the same? The first two indicate wax or
soap still on the vehicle. If it stays on, then that indicates a hard water stain and the vehicle needs to be detailed with polish, wax, sealant, etc.