needsomeadvice

Looking for input on the home urine thc tests (50 cutoff). I bought a bunch of them from a medical supply site. I've been "cleaning out" for about 3 weeks and am always testing negative. However, my test line seems to fluctuate quite a bit between being pretty faint to being much closer to the control line. Who has experience with this? Does faint mean it's hovering around 50? If there's a line at all should I just stop worrying? (see my other post if you want more detail). Thanks guys!