I’m not sure what to do with this patio, the sealant is old and separating some from the aggregate. My gut tells me HW mix on the algae under the stairs and the rest, but wondering if a surface cleaner will take it up too. He said stripping it off would be fine.
I clean aggregate sidewalks all the time. Surface cleaner is fine.
I would HW mix or maybe spot treat problem areas and clean. Set expectation that yes, if sealer is old and already coming up, more is probably going to when cleaning.
Do you typically find it all comes up or just patches? He may not be thrilled with some left.
I have only clean 1 sealed patio that was failing. It was an acrylic topical (surface) sealer. Before I started you could see spots of various sizes where the sealer was missing and spots that were still shiny. Some of the spots after cleaning were larger and some areas had new spots.
Think of it like getting a sunburn and your skin peeling. Some areas it will peel in very small pieces, but then you might tug at a piece and a large section of dead skin pulls off all at once.
When the sealer is failing and cracking and peeling away, any cleaning done is going to increase that. I doubt it would all come off unless you applied some kind of stripper before and even then, it won’t be 100% removal in a single cleaning. Stripping can be a pita depending on several factors. If the customer wants it all off, that is a much different job, than just clean it and get rid of dirt/mold. Heat would def help in stripping.