Bought a used 200 gal glass tank that has major Coralline residue on front pane of glass. Tried SOAKING WITH VINEGAR & SCRAPING with a RAZOR BLADE with NO RESULTS! This IS NOT your normal soak for 2 hours in vinegar & easily scrape with a razor blade!!! On another forum a reefer said he used ‘Bar Keepers Friend’ & had fantastic results! My question is : Has anyone used BKF & had good results? Or... has anyone else here had my similar situation & had something work for them? PLEASE NO COMMENTS ON USING A RAZOR WITH ELBOW GREASE & VINEGAR!!! IT DIDN’T WORK!!! Lol Thanks ahead of time!