I have never relied totally on one method. I have used the potable aqua tablets to pass a test but I also do other things to make sure. Several days before a test I increase my intake of vitamin b12 and b6. These vitamins have the effect of inhibiting the binding of THC to the fat cells. Also, drink a TON of water to flush yourself out, and take the vitamin b. so you're basically pissing water. Clean yourself out.
Also, niacin helps but don't take too much. Again, start a few days before. I keep a bottle of clean-out handy just in case. It is a creatine based drink (flavored) with heavy vitamins. The way this works is the creatine coats your stomach and urinary tract. No new leaching of THC molecules into the urine while this coating is present (time sensitive, usually a few hours). Then drink water, enough to be able to piss clean. Don't smoke prior to the test (3 days). Your levels will be too high to pass it although I know someone who passed using Vale and smoked the day of the test. Good Luck
Also, niacin helps but don't take too much. Again, start a few days before. I keep a bottle of clean-out handy just in case. It is a creatine based drink (flavored) with heavy vitamins. The way this works is the creatine coats your stomach and urinary tract. No new leaching of THC molecules into the urine while this coating is present (time sensitive, usually a few hours). Then drink water, enough to be able to piss clean. Don't smoke prior to the test (3 days). Your levels will be too high to pass it although I know someone who passed using Vale and smoked the day of the test. Good Luck