My best results have come from using a product called "Fungus Eliminator" made by Jungle Laboratories. It's marketed for ponds, but you just use a proportionally smaller amount for your aquarium. I have used it on snapping turtles several times and it works very well. I have also recommended it to others here at Kingsnake over the years and they also have had great results, one lady saying that I saved her turtle's life with it. Just use the correct amount. Don't be one of those people who think "If this much is good, twice as much will be twice as good." Good luck.