A few suggestions. 1. Get a TDS meter and check your RO water. You should get a value less than 40 parts per million (ppm). 2. Dump a little bit of all of your waxes, sealants, polishes, and drying agents out their feed lines at the injectors. Then fire a
soap, hopefully none of the lines pulls up. If it does then you have a bad Danfoss and have an anionic and cationic cancelling one another out. Basically your
soap passes are useless. 3. Check your volumes to be certain you don't have a clogged tip. 4. Call your
soap rep and tell them what is happening. If they don't come to fix it, find one that will.
You asked what the low pH does. It is an acid that thins the road film to allow the high pH and surfactants to work better. Once the layer is thinned the surfactants temporarily release it from the car and dissolve through the road film. Then the high pH removes it. Most high pH's use hydroxides to clean. When a hydroxide meets an oil or fat like road film it bonds with it and drags it off the surface of the vehicle. If the film is thin enough it breaks off and ends up in your pits. If the film is too thick, the hydroxide can't pull it off and it will soapanify. This actually thickens the layer turns it white and can only be removed by friction.
I hope this helps. Your chemical rep should know all this. If they don't then see suggestion 4 above.