I'm so glad Bubbles made it through the night.
Clean water is a great help to him. For us it would be like getting out of the smoggy city into the countryside.
I would treat his water with API Stress Coat or Seachem Prime. Both are very good water conditioners that detoxify chlorine, chloramines, and heavy metals. A lot of water conditioners out there don't detoxify heavy metals. Also, both neutralize ammonia by binding it with an agent to turn it into the less toxic ammonium. The ammonia is still there so you still have to do frequent water changes, it's just in a slightly less toxic form. Stress Coat also has added ingredients for helping fish heal from injuries etc. too.
I hope Bubbles continues to recover, I'll keep my fingers crossed.