Fermentation bucket too small?

I just finished brewing a brew that calls for 6 gallons of water. After dumping all the water in the bucket and ingredients, I notice that there's about 1 1/2 inches of free space from the very top... Does anyone see a problem with this, maybe with future krausen formation? I figure I'd ask this before fermentation actually took place. Suggestions?

i did this once and it made for a BIG mess in the fermentation closet when it blew off the airlock.

So I should siphon a gallon or so?

Can you rig a blow off hose and bucket? If so, that's what I'd do.

If you have fermcap-s, or can get some, I would try that.

I actually do NOT like the idea of just rigging up a blow-off because with that much headspace you are going to be blowing off all of your good krausen.

I was also thinking of blow off hose but didn't for the exact same reason. I don't have any fermcap, but I can get some after about 3 days... Probably too late

After a year of brewing, I decided that the standard 6.5 gal "Ale Pail" fermentation bucket doesn't have quite enough space for the krausen. I bought three of US Plastic's 7 gal buckets off their web site. I have brewed several dozen batches in these buckets, and have yet to have a foamout....just using a regular airlock. You can get colored lids with these buckets that makes them easy to tell apart, and the lids have a real live neoprene 'O'-ring in the lid that provides a positive seal. The three buckets & lids were about $32 delivered.

Yep... Probably will after this batch. For now should I siphon some beer out? Use a blow tube? Use another fermenter to ferment half the batch? Anything?