First time in fermentation chamber - sour smell

[Gusmedic]

I made a fermentation chamber from a chest freezer and stc-1000 controlling a light bulb in a paint can and a fan. I have two 5 gallon batches in there and it's not s pleasant smell in the freezer. I have since out a cup of baking soda in there. Even when I push on the lid to get some bubbles out of the airlock it's a little sour smell. Is this common? What's causing this and what can I do?

 

[day_trippr]

Are the two batches in the throes of primary fermentation?

You have a rather tightly closed space with a pair of vessels outgassing the effluents of a biological process. Depending on the yeast (or, bacteria, depending on your recipes) you should expect aromas ranging from pleasant to "OMG! Kill It With FIRE!"

Nice try with the baking soda, but faced with 10 gallons of fermenting wort, it's a waste of small money...

Cheers!

[edit] Honest to gawd, now you have me thinking of remoting blow-off tubes outside my ferm fridges

 

[MaxStout]

It could be CO2 buildup from fermentation. That often gives a sharp smell.