Evan and Jay:
Read the instructions of your seemingly cheaper and faster Aquamira drops. Notice that they mention ONLY treatment against bacteria. There's absolutely no mentioning of any protozoa (cysts, giardia, crypto. etc.)!!
Why? Because the chlorine dioxide concentration in liquid form is not sufficiently potent and the EPA forbids AQ from mentioning anything about protozoa!
A few years ago, Micropur came out with higher concentration chlorine dioxide in tablets. Those are allowed to mention treatment against protozoa:
o 15 minutes treatment against bacteria (same as liquids)
o 30 minutes to 4 hours for treatment against protozoa (longer for colder water)
IMO, if the water is near freezing -- then the long treatment time is almost a false sense of security simply because few of us will wait that long (unless it's an overnight treatment). BUT, you should know that the liquid form doesn't even have this level of security -- real or not!
I had personally talked about this with Aquamira rep. I was told that the liquid form could match the potency of the tablet form to treat protozoa as well -- by quadrupling the dosage!! Now, do the math...
For me, I use a combination of UL filter and chemicals as follows:
1. First treat with chlorine to kill bacteria and viruses -- 5 drops per quart -- 20 minutes wait time.
2. Second, suck water through a light and compact AquaMira Frontier Pro filter (2oz weight) -- to block the bigger and harder to kill protozoa -- and also to clarify water and improve water taste (i.e. completely eliminate any chlorine taste).
And since I rely on the filter to block protozoa, all I need are the el cheapo household chlorine -- and not the expensive chlorine dioxide tablets -- which take too long to do their job anyway.
Finally, and you may already know this -- AquaMira itself now sells chlorine dioxide in the more potent tablet form as well. If protozoa are a concern -- and they are in more and more water sources -- then the cheap/fast liquid form that's only good against bacteria is not the full answer -- unless you quadruple the dosage per the AquaMira rep. I talked to.