what about some citrus cleaner
or
time to buy a new bong
friendowl Reviewed by friendowl on . How to clean permanent ring out of bong? I let my bong get WAY too dirty before cleaning it...now there's a permanent ring around the water line. I let it soak for two days in 99% isopropyl alcohol, which normally cleans it great, but there's still some that won't come off. I also tried boiling it, that didn't help. Anything else I can try to get rid of this stain? Rating: 5