[whatcaneyedo]

Keep it up from that sand in an area where the damaged tissue will have good water flow all around and it will heal in time. I've run a trachyphyllia and lobophyllia through a saw on more than one occasion and to get them to heal without any problems I always make sure the cut pieces have good water flow. If the damaged tissue is smothered it will be more susceptible to infection.

A little bit of target feeding with some small meaty food will also help provide it with more energy for healing.

If it has a brown jelly infection already, remove the coral to a bucket of aquarium water and blast off the infected area with a turkey baster then return the coral back to your tank. That usually works but if it continues to spread cut the infected area off with a saw just above the receding tissue.