I have been doing the FAS/DPD test using the Taylor Speed Stir since I got my TF100 kit. Last night I was testing and I noticed once I was done testing and removed the cylinder from the speed stir, it was pink again (this is not due to the few minutes of sitting that the waster will turn pink). I think with white stir pill taking up so much room in the 10ml of water, the spinning white seems to dilute the pink and appear clear before it actually is clear. Has anyone else noticed this or am I just not sensitive enough to detecting the change in color? I repeated the test a few times with letting the speed stir get the water pink, then I took it off and added the 871 reagent as I swirled by hand....I got about 2ppm higher reading. Just wondering if anyone else out there has experienced this...I'm fine adding the 871 while swirling by hand, but I figured the speed stir would give a more accurate reading....