If memory serves me correctly, that appears to be a form of nostocular cyanophyta, which tend to produce the highest amounts cyanotoxins. My advice would be to remove the affected matter from the tank immediately, and to vinegar the wood, and bleach the rock. I don't have experience with any chemicals added to the water for cyanophyta removal, but I will say that be that it's always better to under dose then over overdose. Hope this helps!