This is my first time making sourdough starter. Everything seems to be going alright, the starter is bubbling and rising. I started it three days ago, equal parts water and fresh ground farro wheat flour. My concern is that when I check it after 12 hours or more, there seems to be a thick, hard crust on the surface. Doesn't look or smell like mold. The best I can describe it is that it looks like bread crust after baking.
I have been scooping this part off and continuing to feed the starter (equal parts water and flour). Smells a little fruity/sour (I think how it's supposed to), but other than that it seems ok. What am I doing wrong, and is the starter still ok to use?
I live in a dry, high altitude climate, so I'm wondering if the surface exposed to air is just drying out? Help!!