Deck Measles!

[kuching]

Not Osmosis! My deck is covered with gray spots. The picture shows it where it appears most strongly - on a section covered with non-slip interdeck paint. But the whole deck has these gray spots sometimes merging into puddles. I've tried cleaners, vinegar and bleach to try to get them out. Nada. It seems to have spread too. It started on the forward bow and now is all over the boat in both the gel coat and the non-slip. Any diagnosis and remedy suggestions gratefully received. I should say the boat is in Malaysia so hot, humid and during the wet season -months of rain.