Can pot.meta. lost potency?

Absolutely. Most vendors recommend replacing it yearly. I don't keep any more than 2 years old. I use fresh each year for winemaking and use the older 'stuff' for sanitizer.

Joe

Thanks, Joe, for the useful reply. I wonder would the old stuff even be good for sanitizing. What made me have doubts was that there were no fumes off it when I mixed it up, though usually I find myself choking and opening the windows.

Bofak

No fumes equals no good... :) Maybe your container wasn't sealed well enough and it died over time.

Here is what I do. I rarely go through more than 4 ounces per year so I get 4 ounces at the beginning of the season. I mark the date on the bottles. I make less than 100 gallons per year, usually between

60 and 90. Any leftovers from the year before gets used as sanitizer in a spray bottle. The way I make sanitizer is add 1 teaspoon citric acid and 1/2 teaspoon potassium meta to 1 qt water in a spray bottle. If the sulfite is old I double it.

As to smelling it, it is a good test but I 'waft' it to my nose, I don't sniff. That's one thing I learned a long time ago. Just open the container and uses your hand to pull the smell to your face, that way you won't get a nose-full and a gag attack. The way I make my sanitizer seems to work and i can tell if it's got some power left by wafting. I use this as a sanitizer for beer too even though all the texts tell you it's not good for that. I'm not sure if they ever added the citric to it though. SO2 is useless in a high pH condition, adding the citric brings the pH down and makes it effective. Any acid is fine, I use citric because it's cheap. I'm not saying beermakers should do this, just that we do it and so far so good. We have had beers that were a year old and they were great. That doesn't happen too often though.

Joe