Aquariums and Fish Keeping

Hey! I hate to have my first post here just asking for help, but Im a worried snail papa. My tank has been going for about 2 months now. Its 5 gallon fresh blackwater setup with 8 neocaridina shrimp and 1 mystery snail (as well as a half dozen bladder snail hitchhikers). Herbert the snail had some growth on him today when i got home. This morning it wasn't there but i did just add some alder cones (presoaked) for tannins yesterday. Im thinking its just a microfauna bloom or bacterial growth from that, but I want to be sure. Im still new to having a tank so its all searches and guess work. I went in with some tweezers and gently brushed most of it off of him, it came off in strings of brown clumps. He seems to be acting normal now, just grazing and cruising around the tank so i dont think he's destressed. Anyways thanks for taking the time to read this mess. Any insight would be greatly appreciated!