Now that you mention it, you're right, regular TSP is known for mineral film deposition as well. I was just reading my PBW container and it says "Excellent in dishwashers to remove stubborn stains from plates, plastic, and glass." once again hot water, short dwell time, hot rinse. I think for reasons I chose PBW, like mixing in my glass, utilizing hot water and short dwell times, may make it impractical for an extended soak. Maybe a purpose built liquid chemical that is recycled/reused would be best. Then you could put it in a parts washer with a storage tank and filter as well. Film line on my boro took a week to form, and did come off, fwiw . . .