Turtle Disease

Question
Hello, I bought 3 Mississippi Map Turtles and they are about 2 months old and are quarter size, I noticed about a week ago that one had some kind of White stuff on its skin, I tried brushing it off yet it won't come off, now two days ago I woke up to find out that the turtle had died, now the other two turtles have it on there front paws but isn't as bad, I've done a water test for: Nitrate, Nitrite, GH, KH and pH, they are all normal, the water is not cloudy so it isn't from the tank being dirty.

I'm not sure what this is and don't want the other two turtles to die, so what should I do? Is it Vet needed or is it home treatable?

Answer
Sometimes baby turtles are just ill to start with, but this does sound like a fungal infection from something.

I don't have a lot of experience with this, but if you post the question at http://www.allexperts.com I believe one of their wonderful folk can help!