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Hope everyone had a nice thanksgiving. I wanted to circle back and update this with a little more detail and precision. It's a bit involved but illuminating, I think.
The response of various QAC detecting methods (Bromophenol Blue, Commercial Quat Strips, Saltwater/fresh bacterial growth, etc) was so close in AlgaeFix and Vibrant that I proposed a guess of convenience that the 3.5% "other" in Vibrant might actually be the same or similar active ingredient as the polyquat in AlgaeFix that is 4.5%.
My guess was wrong. The "quat" response to Algaefix and Vibrant is far too similar for a 3.5% vs 4.5% difference. It's much closer than that.
I used a LaMotte QAC titration kit. The indicator gives the "quat" response to both AlgaeFix and Vibrant, but the titration step does not work because precipitate forms instead. So I did analysis of the color change from the quat indicator solution to see if I could find a nice dose-response relationship to AlgaeFix and/or Vibrant.
The QAC indicator in the kit is a mix of Bromphenol Blue and Methyl Orange that both move differently in response to quats than they do for either acids or bases. Quats cause a shift to from a brown to green color.
The spectrum shows two peaks in the "No quat" - the right peak at 591nm wavelength is Bromphenol blue, and the left peak at 464nm is Methyl Orange. Both peaks decrease in response to addition of a quat.
I ran a wide range of concentrations of AlgaeFix and Vibrant to look for a dose-response and figure out what the range of concentrations for useful info is. Below is the response of the indicator vs (log scale) concentration of product.
Blue is AlgaeFix and Red is Vibrant. Stars are the absorbance at 464nm (Methyl Orange) and X's are the absorbance at 591nm (Bromphenol Blue).
Bromphenol Blue seems responsive at very low concentrations, and once it stopped responding, Methyl Orange responded nearly linearly. Using this info I drilled down on the range of concentrations of interest and compared the response of the quat indicator to AlgaeFix and Vibrant.
The results are below: The amount of the "quat" response from the Lamotte indicator is exactly identical between new bottles of AlgaeFix and Vibrant.
The X's showing Abs at 591nm (Bromphenol Blue) is super linear with concentration up to 0.100uL of product, and the stars showing Abs at 464nm (Methyl Orange) is nearly as linear from 0.100 to ~0.200 uL. Both chemicals in the indicator respond identically to the same concentrations of AlgaeFix and Vibrant.
(Top or bottom is AF and the other Vibrant)
This is such a phenomenal coincidence that it is unlikely to be a coincidence at all.
(If anybody still has a bottle of Vibrant that has caused serious losses in their system, it would be straightforward for me to check the concentration of the quat-like substance in it, to see if it's an anomalously high "bad batch" or not.)
The response of various QAC detecting methods (Bromophenol Blue, Commercial Quat Strips, Saltwater/fresh bacterial growth, etc) was so close in AlgaeFix and Vibrant that I proposed a guess of convenience that the 3.5% "other" in Vibrant might actually be the same or similar active ingredient as the polyquat in AlgaeFix that is 4.5%.
My guess was wrong. The "quat" response to Algaefix and Vibrant is far too similar for a 3.5% vs 4.5% difference. It's much closer than that.
I used a LaMotte QAC titration kit. The indicator gives the "quat" response to both AlgaeFix and Vibrant, but the titration step does not work because precipitate forms instead. So I did analysis of the color change from the quat indicator solution to see if I could find a nice dose-response relationship to AlgaeFix and/or Vibrant.
The QAC indicator in the kit is a mix of Bromphenol Blue and Methyl Orange that both move differently in response to quats than they do for either acids or bases. Quats cause a shift to from a brown to green color.
The spectrum shows two peaks in the "No quat" - the right peak at 591nm wavelength is Bromphenol blue, and the left peak at 464nm is Methyl Orange. Both peaks decrease in response to addition of a quat.
I ran a wide range of concentrations of AlgaeFix and Vibrant to look for a dose-response and figure out what the range of concentrations for useful info is. Below is the response of the indicator vs (log scale) concentration of product.
Blue is AlgaeFix and Red is Vibrant. Stars are the absorbance at 464nm (Methyl Orange) and X's are the absorbance at 591nm (Bromphenol Blue).
Bromphenol Blue seems responsive at very low concentrations, and once it stopped responding, Methyl Orange responded nearly linearly. Using this info I drilled down on the range of concentrations of interest and compared the response of the quat indicator to AlgaeFix and Vibrant.
The results are below: The amount of the "quat" response from the Lamotte indicator is exactly identical between new bottles of AlgaeFix and Vibrant.
The X's showing Abs at 591nm (Bromphenol Blue) is super linear with concentration up to 0.100uL of product, and the stars showing Abs at 464nm (Methyl Orange) is nearly as linear from 0.100 to ~0.200 uL. Both chemicals in the indicator respond identically to the same concentrations of AlgaeFix and Vibrant.
(Top or bottom is AF and the other Vibrant)
This is such a phenomenal coincidence that it is unlikely to be a coincidence at all.
(If anybody still has a bottle of Vibrant that has caused serious losses in their system, it would be straightforward for me to check the concentration of the quat-like substance in it, to see if it's an anomalously high "bad batch" or not.)