Repair oxidized beer?

[ol' rummie]

Today I pumped a batch of beer from my primary to my secondary via diaphragm pump. Not paying attention and working on other things, I didn't notice that the beer flow was over, but the pump was still going, could hear the beer bubbling in the secondary.
Is my beer ruined? Could pumping CO2 into the secondary right away help?

 

[ajdelange]

Yes, it might. If it sparged with CO2 (or nitrogen or anything oxygen free) any oxygen which is dissolved (i.e. hasn't had time to react) should move into the CO2 and be swept out. Staling takes place over time (but the rate depends on the amount of entrained oxygen) so there is a chance this would help.