I didn't use a broom yet, but did spray it down twice with the jet setting, and it helped. I can see it's still discolored and there are areas that are definitely stained with what look like smaller "droplet" shapes. I will wet down and scrub with a broom tomorrow.
We also cleaned our filter for the first time and saw that there was no air relief tube or air relief valve screen on the manifold, and let the warranty manager know. He was going to reimburse me for buying one. The hole where the tube goes on the manifold was clogged with dirt. I thought they just didn't install it at all, but later found it sitting on the bottom of the filter container. So it probably wasn't on there, ever, and fell off during installation.