Skimmer just freaked out on me..Why?

I was feeding my fish and checking on my tank tonight and the skimmer overflowed on me. I cant figure out why. When I feed my fish I turn off the powerheads but I leave the return and skimmer on. I have always done it that way and have never had a problem. Well, tonight I checked the water level in the sump to make sure my ATO was working, checked the temp, and everything was fine. I turn off the PHs and fed frozen Marine Cuisine, that was defrosted and rinsed with RODI water, just as I do every time I feed. As I was walking away, I noticed the pump light on the ATO was on. I opened the cabinet and discovered the skimmer overflowing. I have no idea why. Nothing but the food was added to the tank and no other maintenance was done. Only food went in the tank. FYI, the ATO kicked on due to the turbulence in the water in the return section due to the skimmer overflow.



What could have caused this? Is it common practice to turn off the skimmer when feeding?