Does carbon bleach your corals ? (Kent carbon recall)

[Casey8]

I was using Kent reef carbon corals for years without any problem until 2 days ago. I did water change on Monday evening, everything was fine and normal as usual. Tuesday afternoon, I changed the carbon. I used 1 cup for 100 gallons as instruction and as I normally do, so I am sure I didn't overdose it. But Wednesday morning, woke up and looked at the tank, all my sps corals were bleached. I did 25% water change right away. Today, I did another 25% water change because the corals look even more bleached. Even the hardest coral I have for more than 3 years and has been growing to almost 10 inch is also bleached more than half way I used to buy the smallest size of Kent reef carbon, but this time I bought a 1 gallon container, and that was the first time I was using it on Tuesday. I don't think buying smaller size or bigger size is different from the quality of it. But I had turned off the carbon today, because I thought it must be from using this carbon, there is no reason for me to think anything else. Checked the water quality, everything was fine.
I had spent too much time and money on corals. If I loose all the corals this time, I think I will go with fish only tank. I have been unlucky with them
Hope anybody here can give me some clues what is happening to my corals.