Zep Drain Defense Enzymatic Drain Cleaner Powder - 18 Ounces - ZDC16 - Safe for Pipes and Septic Systems, Pack of 1, white

Had the same problem. The only thing that worked was an enzyme drain cleaner. Run some hot water for a couple of minutes then drop a couple caps of this stuff in and let it sit over night. https://a.co/d/0aedgb7p