Thanks all. But to clarify. The known negative samples such as the tap water were performed on two different dip strips made by two different companies. The one I trust has a solid test line. The test I'm skeptical about has an extremely faint line even with tap water. That's why I keep questioning my own test. I test clean on both tests one day. The next day after one hit the trusted test still has a solid test line and the test I'm skeptical of has no test line or so damn faint that I can trust my own vision to whether its really there or if I'm imagining it. IT's THAT light after one hit. I thing I have a crappy set of strips! I'll run another set of test in a day or so and see if I can post the pics.