I guess this was a fail for me since there is mold on top. I know some say to take it off and not to worry, but I’m a better safe than sorry type. At first I was burping every day, but after 4 or 5 days and it didn’t seem any different I did a Google search and found conflicting information. Some sites said burp, but others said under no circumstances should you remove the lid. I guess I need to do more research.