There's two vets near us one who supposedly have a reptile specialist in on Thursdays and another who deal with reptiles but the guy just reads from a book. Have had previous bad experience with both so don't trust them.
The white stuff seems to be more one day less the next and does seem to be coming off in the water, could it be skin shedding? because when we got them they had stones and slabs in tank but all covered in green alge and water slightly green. Would change of environment have an effect? Have tried to take pic of it but its not showing up clearly.