Recently used three different brands of hose end moss & algae killing
sprays on the roof from a ladder. All had potassium salts of fatty
soap as the active ingredient because that was what I wanted to use.
The Safer brand had 40% of the active ingredient while the other two
brands plus one brand I didn't use only had 22%. Prices were about the
same for all brands.
The Safer and Garden Safe brands had nozzles that only allowed a fan
spray to be used. The Bonide brand had a nozzle that could adjust from
flat spray to stream and the stream position allowed the spray to
reach significantly farther which was very important to me for the
vaulted section of the house roof.
I don't know if the Safer brand could be poured into a Bonide bottle
and work properly as it's a "thicker" liquid than the 22% solutions.
If the Safer brand will reach everywhere you need it to that's the
brand I'd recommend. If you need a spray that will go a farther
distance I'd recommend the Bonide brand. I didn't use the Lilly Miller
brand, which is 22%, and don't recall whether it had an adjustable
stream like the Bonide brand.
Had rain once since spraying and dead moss came off all the roof areas
sprayed with any brand and I haven't looked closely enough to say
whether any brand worked better than another though I'd expect the
Safer brand to be more efficienct since it's 40% instead of 22%.
Hope somebody finds this info useful.