It is aiptasia, and it is harmful to other things in your tank, so you will want to remove it ASAP. Joe's Juice and Aiptasia X are chemicals, but they are safe to use. In a way, isn't your salt mix considered a chemical?
If you are really opposed to using Joe's Juice (which I don't think is anything to worry about), you can try injecting boiling vinegar or lemon juice (which are also, basically, chemicals). Other than that, you can try a few peppermint shrimp. They usually eat them.