Simple biology. You are trying to fight biology with chemistry, based on flawed hobby test kits and the myth that glass box hobbyist have believing 0 nutrients causes dinoflagellates. You have a 30 gallon tank with multiple fish that you feed large amounts of food. Regardless of your test kit readings, you have an excess nutrient problem, adding Dino X might kill something but that will release more nutrients in an already polluted aquarium. Clean the rock, crud, and detritus; stop adding stuff and get back to the basics.