John, you beat me to it--Katadyn Micropur has been around (with EPA approval) quite a few years longer than the Aquamira ClO2 tablets and, yes, it is chlorine dioxide.
I read reports a couple of years ago, shortly after the Aquamira tabs came out, that both brands are made in the same factory in Spain and are therefore probably identical. I have no idea whether this is true, but it seemed like an interesting factoid at the time. That is why it stuck in my memory.
While I know that the liquid Aquamira is a little cheaper, I see no reason why anyone would want to use that instead of the tablets, considering all the fuss and bother. It may be that people are misled by the treatment times on the label. As pointed out in the article, the liquid is approved only for bacteria and viruses, and the treatment time reflects that. I hope that Aquamira gets the EPA approval.
It would be wonderful if a reputable source would test the ClO2 treatment times to kill giardia and crypto cysts in CLEAR water at, say, 45*-50*F. That's the condition of most of the mountain water that I encounter! As it is, we know that the treatment time is 4 hours for the worst possible scenario, turbid water at 40*F.
Katadyn now says the treatment time for protozoan cysts in clear cold water is 2 hours, which is a help. I personally would rather carry a lightweight filter such as the Sawyer Squeeze or my homemade gravity setup using a Katadyn Hiker Pro (6 oz. including the dirty water bag), see Cola Vaughan's setup at
rather than carry a liter or two of extra water undergoing treatment. Of course if you're on a dry ridge with no water sources during the day, you're carrying the water anyway. Most of the places I backpack, though, have a water source at least every hour.
None of this will do you much good, of course, if you don't wash hands before handling food and after toilet functions, and resist the temptation to share gorp that may have been handled by unclean hands. There was an outbreak of Norovirus on the AT this spring, spread by unclean hands, probably not the water.