Anne - I would suspect that the Black Powder is contributing to your issue. If you look at the ingredients of Black Powder from the website,
Marc Weiss Companies - Black Powder, animal by-products is listed. Awhile back I heard the black powder contained some form of beef by-product, but I don't recall where I heard that from (oh rumors, rumors). However, obviously, based on the website, there is some form of animal by-products in it. If you happen to have a phosphate test kit, then put some in salt water (test the water for phosphates before hand) and then test the phosphates with the black powder in it. I'm guessing it's high. Read through this thread
Dinoflagellates - if you scroll down to post #12, you'll find another reefer's experience with the same product.
If you feel it is necessary to feed your corals, the reefroids seem like a better way to go. At least, according to the manufacturer, it is made of a strain of zooplankton, and other marine planktons, which sound like a much better choice than fermentation derivites of "Citrus leaves, yeasts, animal by-products".