Hi, I purchased 2 pieces of Mapani Wood to use in my freshwater tank and have followed the directions to soak thoroughly changing the water over and over until the water remains clear. I placed the "driftwood" in my 55 gal tank and after a day, noticed that a scum/slime had formed on it. Took it back out of the tank and washed it off and started soaking it again with frequent water changes. Yesterday I put the "driftwood" back in my tank and now it has the film again and in some portions contains little bubbles. Is this something I need to worry about? Has anyone else had this experience? Thanks so much!!