I got a Chinese elm bonsai as a surprise present around two weeks ago, but I'm having some difficulties with it. As soon as I got it I read into several care guides. I stuck a toothpick in the soil and only water it when the toothpick is dry and mist it once every 3/4 days. However, the bonsai seems to have powdery mildew on the surface of the soil. A week ago I watered it with 1 part milk and 5 parts water and the mildew took 6 days to reappear but definitely less worse than before so I guess it's working. But now some of the leaves turn this weird brown color around the edges. They feel dry to the touch, curl up after a few days and fall off.
The sun is not very bright, but I still only mist the tree in the very early mornings.
Should I water it more or less (with or without milk)? Is it the mildew causing this? Or should I stop misting the leaves even though they appear to be quite dry and discoloured?
Also I noticed quite some dead leaves and twigs in the soil. Is this helping the mildew thrive, should I repot the bonsai?
Lots of questions and lots of obliviousness, I know, but could someone please take the time to help me through this :'(