I've had Seborrheic Dermatitis since I was 13 and have been suffering ever since... I'm 19 now and I have been using fluocinonide for the longest time and it has helped but not very much. It's incredibly demoralizing to have this condition and really a killer for self-esteem. I don't believe I have a severe case of dermatitis but I would say it is medium and it is on my facial areas. It does seem to spread slowly to other areas and that is even more of a hit to me. Initially, it was just my scalp then in 2009 it spread to my facial area and has been there ever since. Gladly it hasn't migrated to other parts of my body.
Now that I've given you my life story LOL! I will attempt what you suggest with the Sea Salt . Interestingly enough my mother has been telling me about Sea Salt forever and I have always considered it to be homeopathy and have never considered it working. I am at a point now that I will try anything to fix this problem as it is impacting my life in unacceptable ways. I will report back and hope that your method is plausible and may even be the solution.