It's hard to tell if its bacterial or fungal (it looks both white and red in your picture), but it's definitely not good! I'd start a broad spectrum antibiotic like Maracyn-2 ASAP in a hospital tank. If it's fungal, dips in Malachite green might help too.
The infection is actually black and fuzzy and on the gill cover. I think the white you are seeing is the exposed gills or flesh underneath.
I did another dose of triple sulfa this morning and it looks like black fuzzy stuff is turing a bit white on the ends today. If it continues to improve I'll continue the treatment for 1 week as suggested on the box.
Is there any harm in doing a maracyn-2 or furan-2 treatment after finishing the triple sulfa?