CONSULT PLEASE

hello so i made a starter two days ago, and today (around 7pm) is my third day of feeding but my starter already grew/raised and theresa layer of water… also it smellllsssss sourrrrr. what does this mean? i used all purpose flour and filtered water… THANK YOU also i did partially cover w a paper towel

hello so i made a starter two days ago, and today (around 7pm) is my third day of feeding but my starter already grew/raised and theresa layer of water… also it smellllsssss sourrrrr. what does this mean? i used all purpose flour and filtered water… THANK YOU also i did partially cover w a paper towel