Need help with mold/mildew on a Nautica RIB
I think I made a mistake and I am hoping it can be corrected. I have a 12 foot Nautica Rib (grey tubes) that I purchased new about 9 months ago. All was fine until a few months ago when I sprayed 303 protectant on the boat while it was still wet from a rinsing and I left it to dry on its own. The boat is stored outdoors in on a floating dock. When I came back a couple of weeks later, the top half of the tubes were covered in small orangish-brown dots. Not sure if it was mold or mildew, and I assumed that I sealed the moisture in with the 303 which caused the problem.
After trying a few different methods including diluted bleach, I was able to remove the spots with 3M mildew remover. However, they now reappear every week or two. Is this mold or mildew? Is there anything I can do to permanently remove this? I would sincerely appreciate any help I can get. Thanks.