The Mrs. Wages has been quite proven over the course of several years now. It's doesn't seem quite as pure but good news is the impurities will stay at the bottom.
Because I don't use lots of it and does last quite a while for me, I just as soon buy the ESV brand which doesn't leave that gray impurities like the Mrs. Wages. For me, If I were to average it out over a years time, the Mrs.Wages route only saves about $10-15 a year so really wasn't worth it to me over the ESV. If I used on a much larger scale with more of a savings I might would switch but doesn't make alot of sense to do so....
From Roch Post:A side note: When you want kalkwasser, you are best off buying 'pickling lime' It costs 1/5th as much as the aquarium store variety and is the exact same thing. Walmart south has it with canning supplies in the fall and authentic Mexican food stores may sell it under the name 'cal'. (It is the first step in turning corn into tortillas. The lime step is what changes corn from pure roughage to actual nutrition.)<!-- / message --><!-- sig -->
So 1/5 of $20 so you save $15 bucks a year for most, that is if you can find it local as it is seasonal. If you have to order online then even less of savings because of shipping.
Personal choice really as for most of us don't use enough to your quantify much of a savings.
Just looking in the bottom of the container at the undisolved though it's easy to tell that it isn't the "exact" same thing as the quote suggests. Since the impurities stay at the bottom though probably not of concern.