Best chemicals to clean these marks off pillars?

Afternoon all, 

Quote on a window cleaning job today and the client also has some stone columns & horizontal pillars in the attached photos with some black marks. Didn't have my gear on me so couldn't try to remove them with water and a scrub on the spot, anyone had experience with this sort of thing? I guess it looks a little like lichen but I'm hoping it doesn't need to be pressure washed off — what chemicals would you reccomend? Hypo? Virosol? TFR? Thanks in advance!

Looks like black mould or mildew , hypo mix or black mould spray will kill it wfp would probably remove it but leave spores behind .so would use a mix it kill it .

I think it's mould, so I would softwash with 4 & 1 hypo and it should disappear in less than an hour. My Q-clear worked a treat on moss but the lichen is still there so I treated my porch roof with hypo to see if it removes the lichen. Got a heavy contaminated moss roof job next week so will use Q-clear and report my findings.

Thanks for the tips guys!

Not my field at all, but I would want to know what those tiles are made of first as they look screwed or bolted to those pillars