Like most of us, I read about Formula 409′s near-magical ability to kill New Zealand Mud Snails.
I also read that the Formula 409 used wasn’t the everyday Formula 409 you buy in the stores, but a lot of fly fishermen apparently didn’t get that last memo, and word has spread about Formula 409.
Which – as it turns out – doesn’t work very well at all. At least according to this from the Center For Aquatic Nuisance website (The Story of Formula 409):
The news that CDFG said that Formula 409© would disinfect wading gear spread rapidly through the fishing community. Many anglers began to carry spray bottles and have become religious about cleaning their boots with Formula 409© after each trip.
Unfortunately, from the very beginning, anglers failed to understand that the measures needed to disinfect boots using Formula 409© went far beyond just spraying the boots.
The first problem for the average angler is that the disinfection method used in the CDFG experiments were never adequately communicated by the fishing community.
The CDFG Formula 409© experiments were conducted by taking boots and sealing them in a waterproof bag along with 2 – 2 ½ gallons of 50% Formula 409©. The bag was then sealed and vigorously shaken to make sure all boot parts were soaked. The boots were soaked in the chemical solution for a full five minutes. Only when thoroughly soaked for at least five minutes did the 50% Formula 409© prove to be effective at killing NZMS.
A second misunderstanding that many anglers experienced was that the 409 compound used by the researchers was a completely different formulation than that which is sold in spray bottles. Formula 409© is made by Clorox Company and they actually make five or six different chemical combinations that they market as varieties of Formula 409©. The Formula 409© used by the CDFG researchers was a special degreaser formula that is not what is typically available.
As word spread that Formula 409© was an effective disinfectant the Colorado Division of Wildlife (CDOW) determined that they needed additional information before they could recommend its use. Consequently, they conducted a second series of experiments using Formula 409©. Their research was published in a peer-reviewed article published in North American Journal of Fisheries Management magazine titled Application of Household Disinfectants to Control New Zealand Mudsnails .
The CDOW researchers compared the efficacy of treating with Formula 409© to treatments with the disinfectant Sparquat, a disinfectant not commonly available to the public that is used by some agencies to disinfect their equipment. In the CDOW study the researchers discovered that Formula 409© was only effective in killing mud snails when used at 100% strength in a soak for a minimum of 10 minutes. These researchers questioned the previous claim that a five minute soak in a 50% concentration was adequate to kill the snails as their work showed 100% for 10 minutes was actually required.
The story also noted a few other unfortunate realities for fly fishermen:
- Spraying any kind of Formula 409 isn’t effective (only soaking in a bag works)
- Formula 409 isn’t a universal disinfectant; its effectivness against other invasives is unclear at best
- Only the very hard-to-find “degreaser” version of Formula 409 proved more than marginally effective – not the spray stuff
OK. It’s not exactly stellar news in the war on invasives, but if you’ve been spraying standard Formula 409 on your wading boots and calling it good (against all invasives), you’ve been deluding yourself.
Dang.
See you back at the lab, Tom Chandler
UPDATE: Ralph Cutter has good info at his site, though it’s clear that the degreaser style of Formula 409 is pretty hard to come by…
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