I don't know much about Sugar, but I want to contradict some info above.
My wife and I live permanently at sea on our sailboat. We spend a lot of time in the water, kiting, spearfishing etc.
Here is what we have learned:
Any disinfectant containing Iodine (Betadine etc) should not be used to disinfect a coral injury.
Coral polyps which are microscopic, love saltwater, warm temperature, and iodine.
We have noticed the healing of coral injuries is slower when using iodine.
For stings, on basically anything that can sting you, from jellyfish to stingrays, the treatment is heat.
Millions of years of evolution between the temperatures found in the sea has limited these creatures cells ability to handle extreme temperatures.
The nemaoblasts, nematocysts, basically stinging cells are made up of various parts, but the venom is usually a protein.
They are triggered in various ways, electrical, chemical, physical etc, but are not triggered by the same salt water they live in.
Any chemical, ammonia, pee, windex, whatever, is more likely to trigger a mass discharge of venom.
We use the same sea water, heated to about 40 degrees C which is about as hot as you can handle, it must be uncomfortably hot!
It changes the protein already injected, and that on the surface to endoplasm, basically soup, and as such cannot sting you any more.
If we are out snorkeling, and far from the main boat, we will take a wet rag, and hold it on the engine block of the outboard motor to heat it. If near home (the sailboat) a wet rag in the microwave, or in a pot on the stove. Fresh water also works but not as well. 3 or 4 applications will suffice, relief is almost immediate.
Its important to be has hot as possible without actually burning.