Removing moss from the roof (cleaning, slate, leaking, old)

[AAVC]

We received a letter from our home insurance requesting that we remove the moss from the roof. This is a home built in 1938, with a slate roof that is fairly old but not leaking yet. I reached out to various contractors, and some use bleach, some us sodium hypo-chloride for cleaning. I was told that the sodium hypo-chloride will leave white marks on the roof that will be washed by rain over time. Any thoughts on that? Will it really be washed by rain? Any advice in this regard? Thanks.

[K'ledgeBldr]

https://www.city-data.com/forum/hous...g-my-roof.html