I fed 1 cube of mysis in the last 48 hours to 8 fish
Not saying that that was the problem but I always tell people not to feed anything.
I know many people that think their fish will die If they don't get fed everyday to which I tell them that I know people that Feed their fish once a week and they are fine. So not feeding your fish for a few days isn't going to harm them.
It takes time for beneficial bacteria to grow.
I read somewhere it can double every day.
1 goes to 2, 2 goes to 4, 4 goes to 8 - 1 Million to 2 Million, etc.
So After Treatment You do a Water Change and use Carbon (Both Take out the Chemi-Clean).
Then Your Beneficial Bacteria that you Lost from the Chemi-Clean Will Start to Grow Back Again.
So before people start feeding the full amount I say
Day After Treatment - Sprinkle in Just a Few Pellets.
Day 2 - Sprinkle in a Few More
Day 3 - Pellets then add Your Frozen Food (Partial Amount)
Day 4 - Pellets then a Little More Frozen than the Day Before.
Eventually you will get enough Beneficial Bacteria Back in the Tank to Do Your Full Feeding Feeding without any Issues like you did before using the Chemi-Clean.
The Slower you go the less likely you will have an issue.
I think that for most tanks this is not an Issue.
Because most people do no have issues with Chemi-Clean but I see a Few Pop up Every Now and Then.
I think the Issues are from People
1. Don't use the Airstone
2. Love to Powerfeed their Fish and Coral
I feel if everyone followed those 2 Tips we wouldn't see threads saying Chemi-Clean Crashed my Tank!