You have a habitat like mine! I clean my water often and use the net to skim out bugs and any dirt. What kind of substrate do you have and is there anything else in your tank where you see mold? Do you have algae? If you have wood under water I'd put it up high enough so its out of the water. I have a wood log that is sitting on rocks and its not in the water. I would clean your water more and remove anything that absorbs water. Hope this helps.