You have to be careful with Food and the Waste that comes after the Food.
With Lowered Beneficial Bacteria in the Tank there is Less Bacteria to Process the Waste so it is much much easier to Get an Ammonia Spike which would cause problems.
Look at it this way.
After using Chemi-Clean Treat Your Tank like it is a Newly Set Up Tank that is very very sensitive (I don't care if the tank is 10 Years Old. Pretend you Just Set it up Yesterday and Take Care of it Like a Tank that was Just Set Up.
As I am sure most of you know Newly Set Tanks are Much Much Much more Prone to Ammonia and Nitrite Spikes because there is Not Much Beneficial Bacteria.
When you set up a New Tank you Have to be very careful how much you feed.
You start feeding very little and slowly ramp up your feeding to safely cycle a tank.
My Friend Used Chemi-Clean but kept doing his same "Power Feeding" Regimin as though his Tank was not being treated with Chemi-Clean.
He Blames the Chem-Clean for Killing his Coral.
My Theory was his Overfeeding Killed the Coral.
He is too scared to use Chemi-Clean anymore though so I can't really Test My Theory Though