Looks like algae film. You can dip in h2o2 with sw, try a 1:5 ratio
Not sure what the bubbles/warts are on the dark patches. I hope not eggs of some critter.
Or, this method is more effective for cleaning
You can stand the frag vertically out of the tank and apply hydrogen peroxide directly. Use a small paintbrush, dip in h2o2, and apply downwards from flesh band base to the bottom. Don’t let it touch the flesh band. It’s quite easy to be safe this way if the torch remains vertical because gravity works in your favor.
After you’ve applied to all of the trunk, let it sit in the open for 5 min, then put back in the tank and check after 24 hours. Full effect of cleaning will be within 48 hours. Seeing microbubbles when put back in the tank is normal. It’s the algae and films dying and breaking down
