Cleaning dirty sandstone patio

This is a newly installed patio made of sandstone pavers. Its soft and porous, so you can imagine how deep the dirt has settled in.

How would you clean this? Would a surface cleaner set up with lower pressure nozzles be OK?

I have a 4gpm/4000psi machine. My surface washer is set up with two 2.0 orifice nozzles.

If wanding like deck boards is better, how much pressure would you use?