Can't figure out why this beer exploded?

[bytor2012]

I brewed a hefeweizen on sunday and this morning (Tuesday) I went downstairs to check on it and the lid was halfway off and there was a small mess going down the bucket and onto the floor. I can't figure out why. The og was only 1.038 and I used White Labs Hefeweizen IV yeast.

Anyone care to take a stab at it and enlighten me?

 

[ffaoe]

How clogged up was your airlock?

 

[bytor2012]

Yes, that makes sense as to literally why the lid blew off. But, I guess my question should be why was fermentation so vigorous in such a low gravity beer?
It is my understanding that you only need to beware of explosions or be on guard to use a blow off tube only in higher gravity beers.
Is this a misconception?

 

[inhousebrew]

How clogged up was your airlock?

More importantly what temperature is it at. I don't like the hefeweizen's but I've heard some of those yeasts are pretty notorious top croppers. How much head space in the bucket?

 

[SledgeH]

Yes, that is a misconception (although that is a contributor). Pitching too much yeast, higher temps, clogged airlocks can all lead to this.

 

[ffaoe]

I brew mostly beers under an OG of 1.060 and i've had a lot of close calls. My first ever 5 gallon batch was a blowout, which was around 1.045. Ever since, I always have a sanitized blow off tube at the ready.

 

[jmh286]

As a rule I just put a blow-off tube on for the first week of fermentation. I would rather have it there and not need it than....well you know. I also use this as an excuse to sniff the beer when I switch over to an airlock