I'm so sorry about your toad! I hope he gets better soon.
Unfortunately I would not know what could cause this problem with his eye.
Sorry to cut into this thread, but Griff I too have well water and was told a de-chlorinator was not needed as there is no chlorine in the water. I have 2 white's tree frogs.
I didn't know about the water conditioner. What is recommended for those that have well water?