I had the same issue with mine even after boiling it, it seems to come from the lighter parts of the wood as all the pieces I had that were dark brown were fine, it went away after a week or so for me and really didn't have any negative effect that I could tell other than looking bad.
it happened to me too. But mine was on plants+tank glass. Threw in a couple plants into my RCS and they devoured the algae. Then I took out my fish inhabitants from the algae infested tank and threw in the RCS+ottos for a few days. The algae was gone and never came back.
I had the same problem this week with a rebuild. White fuzzy fungi on driftwood that was sitting outside for a couple of weeks. Probably picked up spores. Looked awful and furry for a week then I put a couple of black mollys in and it's 90 percent gone within 24 hours. Mollys are workhorses! roud: