Killing mold in non-skid

[abl1111]

I've used bleach before, but the mold is very persistent ! Every season I have to get it off again. It takes more than a casual scrub to get it off too. It loves my non skid. I think because the non skid is older ( from 1975 )and a little more porous than newer non skid and the mold can house itself there very well.