WOW I just use a 3/4 electric sump pump in a bucket or drum. SImple and cheap.
KISS
Also My company is enviromentally friendly. No hypochlorides. No bleach.
I must say though, I bet borax kills it pretty good. PS sodium hypochlorite is bleach, man we need some chemists in here.
Yes all Sodiums (salts) harm metal oxide paints and metal surfaces, thats why so much rinsing must be done, + bleach is caustic look for a non-chlorine bleach. I buy all products in powder, WHY PAY TO SHIP WATER ???
P.S.Try this guys (little secret for u) Offer fungacide treatment and a 2 yr guarentee
Do the treatment once a year, saves customer money and is easy bucks for u + maintenece contracts might just add that second crew many are looking for
A little more advice.... Carry aggragate insurance for the roof and know what u r doing before using stuff on your customers. Screwing up a few roofs will put u right out of buisness, espescially when lawsuits get involved.
If you are a soul proprieter they can also sue you and your personal property not just your company (you are the company)
Take your time and learn GOOD LUCK