i wouldnt tell u this if it wasnt true. i LITERALLY just got back from the lab and cam clean. its friday..i smoked dro wed..... u take a packet of certo ( i got the blue package that come with 2 ) put it in the gatorade, mix it up and chug it. then refill the gatorade back up with tea or another gator. ( NOT WATER) water makes ur pee clear and looks suspisious. u pee like 2 times and hold the 3rd pee in untill the test. u try to time it where ther certos in ur stomach for about 1 and a half 2 hours before ur test. DONT EAT!! i passed. i was dirty weD.. O AND THE NIACIN IS A BS MYTH. I LITERALLY TOOK 100 IN 2 DAYS AND IT WAS DIRTY STILL. THE 500 mg too. certo jell works becuase it keeps the thc in ur kidneys. it DOES NOT CLEAN UR SYSYTEM i just traps the thc from coming out of ur dick for a few hours....if u dont believe me go to walmart buy a 12 buck weed test. and the certo and c before u take the real test. thats what i did