All I can really say as far as Certo goes is that there seems to be some property of it that blocks the detection of THC. I have tried many things to falsely pass a drug screen. First off the type of test the lab uses can make a difference. There a few different types of tests that are used for urine tests and some are more sensitive than others so depending on the test used depends if one or more of these remedies are going to work or not. From what I gather niacin does work somewhat to lower the levels of THC in your body because it speeds up the half life of the THC break down in your body because it burns fat. To the people who say that Certo works because the way the individual is taking it and how drinking so much liquid it justs dilutes the sample I think is incorrect. I have tried the crap load of water and or a combonation cranyberry juice, or apple juice and even shots of vinigar and tested positive or inconclusive (diluted sample) for THC on a screen. The first time I used Certo I mixed it with water in a 1 liter bottle. It was so foul I nearly vomitted and could not keep it down. Then I tried mixing it with grape powerade this was a 32 ox bottle. I drank a couple of big gulps and added the 2 packets and drank the bottle about half way down and refilled it with water. I drank it down half way again and refilled with water and drank it all. I went to the bathroom two times and went to my drug screen. I started to urinate in the toilet and at mid stream I started to fill the cup. I passed the test. I know for a fact my urine was dirty before the test I had used a home test just a few hours prior to doing this. I do this when ever I have a drug screen but only if I can not find someone with clean urine to provide me with a sample. The best way to pass a drug screen (obviously would be to not have dirty urine in your own system) is to have someone provide you with a clean sample earlier that day or the night before. I use an elmers glue bottle that has been cleaned out really well and you need to cut the plastic stuff out of it so the hole is big enough to pour the sample in. Have a thermometer ready and a microwave available. Heat the bottle in 5 second intervals and take its temerature. Once its at 105 deg f you can wrap it against your leg inner thigh with an ace bandage or a leg brace. I know it takes me about 15-25 minutes to get to the place and it cools down to high 90's deg by the time I get there. I notice that when I provided a real sample that the thermometer on the sample cup is never in the 90's like body temp its usually 85-88 degrees. Just pour your clean sample in and it should be around that same temp. I have passed everytime I have done this. I hope this helps people who reads this.