
. It did shut down on me for the first time, too.
I get everything ready. Package opened and formed like a funnel, vial wiped clean, lead open. Also I get the timer ready on my cell phone. I put the vial in and press once, shows C1, then press again. When I see C2 I hit the Start on the timer, so I can see where I am with the time. Put the reagent in, tear the package and if anything else is left I put it in, too. Shake gently until I see the time is about 2 minutes and 40 seconds. Put the vial in the checker and press and hold to show the 3 min countdown.
I agree, the powder reagent in that package is a pain. Liquid or a small hard container with powder (like a 1/4 tube size), or powder pressed in a pill would work better for users.
For me, I think that I get the water samples from a wrong location: in the sump, between baffles. Convenient in my setup, but sometime I may get micro bubbles from the skimmer. The shake will keep them in vial and if they get stuck on the inside glass, the reading may be influenced.