If I were softwashing a roof - is there any reason why I shouldn’t capture the mix and pump it back onto the rest of the roof instead of using a large tank?
You’d have a filter before it was directed back to your container. The quantity always starts with what you have in the tank so a filling valve would not be needed.
I think the trick to it is, having as little runoff as possible, so that whatever does run off is not a usable quantity.
Also SH is highly reactive to organics, so if it did interact with organics the recycling wouldn’t be as efficient or effective. Right @CaCO3Girl ?
Surprised it would decay that fast! Interesting.
I think the reaction time is hours but like @Infinity said the goal is to not have enough runoff to reuse.
In addition to reacting with organics, you also have the issue of the chlorine evaporating out very quickly on a hot roof. What you collect from the gutter downspouts will be a lot weaker than what you sprayed up on the roof.
Good point!
I’m glad I asked - this is all helpful information.
Why would you bother, the customer pays for the SH you just spray it.
There’s no way I’d run the sludge that comes out of the gutters I’ve bagged back through my expensive pump/hoses/reel. No way. @MuscleMyHustle is right, if you’re priced correctly then the client already paid for the chemicals
@TexasPressureWashing you rang? Lol!
Yes, this thread is accurate. Let’s say you did collect the runoff, which shouldn’t be much anyway. What you would be collecting has already lost much of the SH to contact with mold/mildew/slime on roofs. If there wasn’t some kind of gunk up there, why would that have called to get it washed?
Organic contaminates and heat would make the SH no longer very effective. I don’t see the point in collecting it to try to use again. The whole runoff probably doesn’t cost more than $10 to make and it would be more than $10 worth of frustration to collect that amount to reuse.
Stay safe my friends 
Thank you! 
I’ve been using slo-mo and on roofs that are very steep or ones with lots of sensitive plants/stained wood or other risky factors I will double up on the amount so it barely runs down, especially tile roofs where it runs quick down the slide between them.
