I've used the weed sprayer method myself a few times and I've also used a pump up concrete sprayer. I've used diluted super clean and I've used diluted HF water-based parts washer solvent in the sprayer. I wish I could say what worked best,but I honestly can't remember.
If you do POR15, do the prep. Water based cleaner phosphoric acid wash,POR 15 top coat. I'm not a believer. Its smoke and mirrors. The prep is the magic not the topcoat. It's an old 3 part system re boxed and introduced as new magic.They used to paint bridges this way 100 years ago.
I couldn't find my concrete sprayer online looked at this one but it doesn't say what diameter hose. A good concrete sprayer has a lot bigger hose than a garden sprayer so it can deliver some volume. Mist on your solution,let it soak wash it off with as much volume and pressure as you can get.
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