For those of you who have access to a well-stocked chemistry lab, here's Susan's formula for the aqua-colored signal flare mixture that defeated Dr. Light in my latest Supergirl fan fiction story (the formula is given in parts by weight):
Barium nitrate 45 grams
Potassium perchlorate 8 grams
Copper carbonate 4 grams
Chlorinated rubber 20 grams
Charcoal, fine powder 4 grams
Sulfur, fine powder 8 grams
Magnesium-aluminum alloy (50/50). fine powder 7 grams
Dextrin 4 grams
I tested this formula myself, and can confirm that it does in fact work very well. And in fact, I've used in my own fireworks displays!
P.S. - Unless you're a member of the Supergirl Team, that's Dr. Ramirez to you!