A hot water power wash with acid is like magic!!!Ok. So with the kleen wall on the brick it is turning brick white. Just keep at it?
I would not sand blast, even if you manage not to destroy something while actually doing the blasting. you will probably be getting sand out of your equipment for years to come. Soda blasting a milder abrasive will probably work, but I still would not recommend it due to the abrasives getting into my pumps, swivels, bearings, hinges ......If all else fails then it is time to sand blast it clean.
I've seen two red brick car washes that were sandblasted, one to remove buildup (I had cleaned it once myself about ten years before and it came clean easily using muratic acid with no damage to the brick), the other that had been painted. Both look terrible now, the brick is badly pitted and porous, the mortar is eaten up, and anything that gets on the brick stains it. And yes, one didn't bother to seal up the room and everything got full of sand and brick dust.I would not sand blast, even if you manage not to destroy something while actually doing the blasting. you will probably be getting sand out of your equipment for years to come. Soda blasting a milder abrasive will probably work, but I still would not recommend it due to the abrasives getting into my pumps, swivels, bearings, hinges ......