I attended the July 2010 meeting of the Aquatic Plant Management Society in Bonita Springs, FL. I met one of the presenters from the U.S. EPA
Ms. Allison Weideman
Branch Chief of the Rural Branch of Water Permits Division
Environmental Protection Agency
401 M St. Sw
Washington Dc, District of Columbia 20460
United States
(214) 665-2200
(202) 252-0500 Fax
www.epa.gov
I asked her about regulations concerning dyes. She told me that dyes are not a pesticide and are not regulated. I also spoke with the Michigan Department of Natural Resources this summer and they reiterated the same statement. "We do not regulate dyes". While you may be true that back in the FIFRA in 1972, 38 years ago which you referenced, dyes were regulated, but I could find not such statement in the current FIFRA(FEDERAL INSECTICIDE, FUNGICIDE, AND
RODENTICIDE ACT)
[As Amended Through P.L. 110�246, Effective May 22, 2008]
http://agriculture.senate.gov/Legislation/Compilations/Fifra/FIFRA.pdf As far as the NPDES guidelines it not applicaple since the dyes are not a pesticide.
Contrary to what you are saying one can purchase lake dyes with Acid Yellow 23. The Yellow 23 is not a significant contributor to the cost of the product, at 1-2% dye content it does not really alter the cost. In Fact because the Yellow 23 is not stable(it falls out of solution) at high concentrations, AQUASHADE is a weaker product than many dyes available on the market. If you try and make a concentrated product containing Acid Yellow 23 the Yellow 23 falls out and you are left with an off standard product. I have also heard of many complaints that the people do not like the Aquashade color, it looks too un-natural. The yellow makes it too green. You might try adding some black dye to the blue to make it more appealing and light absorbant over a wider light spectrum(Some black dyes contain yellow 23).
Now to a couple simple tests.
1. Take an eye dropper
2. Put a couple of drops of blue dye of the products in question in separate quart containers of the exact same amount of water (try and be as accurate as you can with the drops, the more drops the better as this will reduce the error. but not too many as the product will be too hard to evaluate) Try and get exactly the same amount of dye in exactly the same amount of water. As long as the dye solution is not too concentrated you should be able to see through the solution. The darker the solution the stronger the dye products. Repeat with as many products and compare side by side. You can determine the relative strength by diluting the product. For example the Aquashade is 50% when compared to Pure Blue Liquid dye. The solutions will look the same(minus the green tint for the Yellow 23) if the same amount of Pure Blue Liquid is in 1 gallon as compared to the same amount of Aquashade dye in 1/2 gallon of water. By the way the blue and yellow dyes used are the same dyes used to color easter eggs! Spectrophotometers are great as a tool but all they try to do is simulate the human eye.
As far as your other comments in a free market society competition is encouraged because it makes the system work its most efficiently.