I wouldn't try that myself, especially not with employees doing the work. Best bet would be to use a pump up sprayer, or brush and a bucket. You could probably use your soft wash system if it was a big job and you weren't going to be having bleach in your tanks.
I'm having. Very hard time getting gutters to come clean I have tried using a product called green clean and it does not seem to work. I apply it with my 4 gallon back sprayer. But it takes a lot of scrubbing and almost looks like it's taking the coating off as well. Any tips or a better product?
I'm not a big fan of pushing gutter brightening, Its hard to meet customer expectations at the prices we want to charge, especially when employees are doing the work. The biggest problem is surface temperature. It really needs to be above 60. When it is at the lower levels we use Gutter Zap. Spray with weak SH mixture, then Gutter Zap. When a little warmer I like a Citrus Gutter Cleaner from Absolute Chemicals. We're waiting for Oxi Wash to come out.
Like Tim said, it is very temperature driven. Here in the NorthEast, we only offer it in the warm months and I don't offer it unless it is 65 or higher. It really depends on the substrate temp, of the metal you are cleaning. Even thought it is 60 out, it might have went down to 40 overnight and the gutters are still cold. Sometimes you just scrub to hard, because the stains are deep and the paint will be affected. We use F-13 Gutter Grenade, and sometimes Gutter Zap, but I know Purple Power works for some guys as well. You just need to try a few things and see what works for you.