In 200 ml of tank water (I use a plastic 500 mL beaker) add 1/2 capsule of "Fish Amoxicillin", 1/8 teaspoon of API "General Cure" (metronidazole), and 1/8 teaspoon of API "Fin & Body Cure" (doxycycline). Stir vigorously but don't expect them to dissolve entirely. Add coral to solution, stirring every 30-60 minutes to prevent hypoxia. I place the beaker partially submerged in a dark part of my sump to maintain a constant temperature. If the solution is exposed to tank lights, it will turn a cherry kool aid color, so stick to darkness. Soak 1-2 hours.
When I have done this, the surviving coral tissue has returned to normal vigor and regrown quickly. The choice of antibiotics here is based on relatively broad spectrum antibacterial (amoxicillin), anti-protozoan (metronidazole), and anti-atypicals/anti-rickettsial (doxycycline). Please don't pour the solution down the drain when you're done, if possible.