Duncan With Brown jelly. What do I do???

[HungryOven]

I had this Duncan coral for only a few days when one head (left) got the disease. Is it safe to cut off the infected head from the skeleton?
Also, every single euphelia that has been in this tank has died of brown jelly. What am I doing wrong?

 

[greenhorn reefer]

I had a hammer, torch and hybrid all get the jelly. I dipped them daily, aggressively blowing off the dead tissue and jelly. All but the hammer are still alive (8 months later) but they never really recovered to normal. They have little issues like funky tentacles or a funky tips and growth.