Steve do you use the powder or the liquid? F90 liquid is woolsafe approved at 600-1 and above dilition.
I have 2 x 20kl of F90 powder in my shed that I stopped using because I found it never full disolved and always left a scum in the bucket (although this was when I mixed a concentrate to put in my T/M tank.)
I think U/M is woolsafe approved because it dries neutral, I used it years ago and found it OK, but then I cleaned everything with the same chemical.
Mike