What is this? How can I fix it?

This was a couple of days after a surface clean. All I did was a post treatment of like a 3% mix.

I don’t believe this is from you unless you had some oxalic or a different type of acid on those areas. If you already took the blame spray oxalic on the entire area you cleaned to even it out.

Yeah I definitely didn’t take the blame. That’s super helpful. A local pressure washer said the same thing when I asked him. He said “are you sure that was you?” Lol

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Almost looks like efflorescence but I’ve only ever seen efflorescence on brick. I’m speculating here but could it be residual salt left over from when the bleach dried after you post treated it? That wavy look makes me think it’s left over from some kind of liquid that dried

Reapply post treat, let it sit and rinse. I bet you’ll be good. Did you have a surfactant in your post treat? If so, mix a batch without surfactant.

I did have surfactant in the mix…will try this! How long should I let it dwell?

Doesn’t have To be long. If this stain is in fact dried SH then you’re just trying to “rehydrate” what was left so you can rinse it off. Same principal as when a customer says you left a film on their windows.