
So how long is it gonna take us to get under 1 ppm? I waited another 10 minutes after this point (20 minutes total) and took another measurement

Hmm. Why is it so high? I wonder if we've already used up a lot of our sulfites, so let's measure that

Wow, down to less than 50 ppm. We started with 130 * .76 = 98.8 ppm, so we just used up more than half of it. At a little over 1 ppm DO left and with the reduced sulfite concentration, it doesn't look like it can reduce oxygen faster than it's diffusing in at this point. It's possible that we would have gotten below 1 ppm if I hadn't poured the water, so that may need some further investigation.
So obviously this a little pilot experiment and it isn't a full scale mash. However, I think it suggests something very important:
SULFITE IS NOT A CURE-ALL MAGIC BULLET!
You can't just add some fairy dust to your water and expect it to keep your mash and boil under 0.5 ppm DO for 3 hours straight. Henry's law is a bitch, and the lower your DO levels become the faster more oxygen diffuses in. You need to win the battle on EVERY FRONT and your system is only as good as the weakest link in the chain. For me, this means preboil, high sulfite dose, NO splashing or leaky hoses, no copper/iron/manganese etc in the water and some sort of inset lid or mash cap with as little headspace for air as possible.Statistics: Posted by Techbrau — Sun May 08, 2016 2:45 pm
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