Im not a big fan of chemicals. If it was me, Id just make sure you have good water quality (keep up good water changes), maybe add a little salt to the tank. But thats just me and what i would do. Some on here may not agree, so might see what everyone else says..
If you have the room and can do it, Id also take out some of your sand. Looks like it is kinda rough. Give the ray a bare bottom area (twice the size of the ray) to be able to go to and rest up. This will help the areas that are burned so they dont get scratched up any while its healing..
Also, if you dont want the white PVC, can get the grey stuff so it doesnt show up as much and stick out in your tank.