I think the registered dye products that use acid yellow in the formulation do so for a GOOD reason. I suspect that the combination of acid blue and correct amount of acid yellow together produce a light filtering feature that inhibits most green plant growth. The light filtering ability of the blue & yellow combination removes red and orange wave lenghts of light. Red and orange wavelengths are primarily responsible for green plant photosynthesis. Blue dye by itself probably does not remove both red and orange light rays and thus minimal plant control results.
Also proper concentration of the dye is important for adequate light filtration. "Light doses" of dye no doubt have less affect on underwater plant growth. I also think bluegreen algae do not use the same light wavelengths as green plants for photosynthesis.
