I have grown tired of swirling my CH and my TA samples. I usually end up spilling a few drops, losing count, and becoming discouraged from the fact that despite my best swirling, it never seems to mix enough. Although I would LOVE to have a magnetic stirrer to aid me in my testing, I don't really see spending $60+ just for this purpose. What would be the harm in swirling the sample by using a small glass stirring stick? Understanding that the testing manufacturers want you to swirl the samples, this is probably because shaking or inversion would skew the results by aerating the sample. As a nurse and drawing from what I know about drug reconstitution, I know that it is possible to stir without aeration. If you asked me, I would surmise that I probably aerate a sample more by swirling the vial and creating splashes in the process than by gently stirring to create a satisfactory vortex in the tube in the first place.