I recently set up a 3 gal picotop aquarium with heater, lites and filter. Cycled it and soaked my mopani wood in water with frequent rinses until clear, then in vinegar water for a day and then in clear water for another few weeks with frequent changes. I have had a very healthy and happy beta for abut 6 weeks now. I'm noticing a soft white fluff blanket growning on the smooth surface of the mopani but not the rougher darker surface, for about 4 days now. Water is still perfect and Captain America (Cappy) is happy. The wood is placed close to the back of the small tank and it is sort of infront of the heater. Temp is at 80 andhas held consisted for weeks now. Anyone have any idea what this whate stuff is? Doesn't seem harmful and I don't want to pull this wood and disturb his happy home if I don't have to.