I have a new deck made of Cox ecolife wood that is turning black. I have tried cleaning the wood with several different deck cleaners and the black remains deep in the wood. The deck cleaners make the wood very fuzzy, like cotton fibers. The cox rep came out to see my deck and gave me some solutions that didn't work. He said it might be copper in the wood but gave me a moldixide to put on cleaned wood. He said it would make the black disappear and not come back. While he was here I ask him to apply and it didn't disappear. The rep said this moldixide was exclusive to Cox and was $100.00 a gallon which he didn't charge me for. I am afraid to use it because it doesn't make the black disappear and it leaves a finish on the wood so I don't think the wood will stain. I am afraid to have this deck stain with Cabots Australian Timber Oil if this is mildew and the black is still going to show through my light color ATO. Thanks for any ideas or help.