Why don't you find out how long it takes for organics to mineralise to ammonia? There is no way anyone dumping a whole can of food in a tank should cause an utter wipeout unless the system is horribly overloaded/badly maintained. You have several hours to try to filter/syphon out the stuff. If you pay any attention to your tank this really sohuld not wipe you out.
I wouldn't expect to get it all out, and I'd expect a bit of a spurt in algae growth but really......
Some peoples tanks seem to crash at anything - what does that tell you - badly maintained, unbalanced, overcrowded.