Starter has a crusty layer

I started a starter last week and the last few days there has been a crustier layer on top with some slight water separation. I have been feeding 20:20:20 every night. I am very new to this. Suggestions as to what I should do?

I started a starter last week and the last few days there has been a crustier layer on top with some slight water separation. I have been feeding 20:20:20 every night. I am very new to this. Suggestions as to what I should do?