How much headspace is too much headspace?

[eyuptm]

Wow, down from OG1060 to 1020 in 48hrs, this is a beast of a yeast!!

 

[Chad Brewer]

If you are reasonably sanitary in your processes, you should be fine. During high krausen, you are blowing off so much CO2 that nothing is going to fall in. I had one clog so badly that when the pressure built up enough it launched the airlock into the ceiling! Sanitize your airlock again and maybe the opening before you reattach it.