Bruce - Diluted Aquashade will not stain limestone but concentrated solution will stain if directly spilled on limestone. I am not sure about the other types of "pond landscaping" that you mean.
Shorty, Aquashade at label recommentations (1ppm) will suppress growth of milfoil, chara and coontail. But recomenations for milfoil suggest that concentrtations can go up to 2ppm for best control. Chara is suppressed at 1ppm. Keep in mind that green plant growth shallower than 2 ft will not be effectively controlled. Coontail is not truly rooted to the bottom so near surface mats of coontail will not be suppressed very much. Early application (before ice formation or just after ice off) of Aquashade for control these plants will be most effective. Keep in mind that monthly renewal of small amounts of Aquashade is the best for keeping optimum light attenuation. Once the standard 1ppm is reached, the monthy small dose should be the original dose divided by the number of ice free months, i.e. one gallon (1ppm) divided 9 (Mar - Dec) = 128/9= 14oz per mo. At concentrations less than 1ppm, expect a respective amount of less plant control associated with the reduced conc.
rmedgar - I would expect fish living in blue dye to be a different hue or color than those living in unstained water. The blue stain no doubt affects how the fish's eye perceives the sunlight. Natural fish coloration is adjusted autonomically by the fish's chromatophores in the skin under the scales.
