Chemical for block paving/patio

[sidekickdmr]

I’ve got about 1/4acre of block paving to clean up, I’ve hired a professional petrol pressure washer and patio cleaning spinny head thing

But before I use this, should I be spraying anything on to break down the dirt/moss etc?

Ta

[sidekickdmr]

Ta, going to grab one of these from my local agri merchants then, much cheaper than amazon etc, assume same stuff?

50/50 ratio to water?

https://www.moleonline.com/deosan-red-label-hypoch...