Since I never know which disease I'm looking at, I go for both Pima and Mela as they are both safe and cheap to use. Instructions do say they can be used together.
Since there is a bit of question about whether there is a connection between the growth on the wood and the fish, I would pull the wood and do a bleach soak. Simple cheap and easy, just to remove the question. Just as I wash my plate before I eat, I do a bleach soak on almost everything that goes in the tank if I have any doubt at all. I find it removes any doubt so that if something does go off normal, I know it is not from something on the new item.