If you smoked marijuana once a day for three days can niacin and a lot of water clean your system?

my question is how long it takes for THC to show up in your system... but for me i know if i smoke on say a saturday, i can pass a UA by monday by just drinking a lot of water... but then again i am 5'9" 145 lbs n have a high metabalism so it really just depends on how much was smoked, your body fat percentage, and your metabalism