Carbing during fermentation and cold crash

[marjen]

So I have a question. I usually start my carbing naturally in my unitank. Generally I will close the blow off valve around day 3-4. I am surprised that even with only .010 points or so left how much pressure builds up. Pressure has gotten as high as 17-18 psi. My question is what to do when I cold crash? This last beer was at that level and now that its in the keg it is overcarbed and somewhat foamy. I know 17-18 psi is low when I am at 70 degrees or so but as I bring the temp down, that now becomes higher than i need. Should I just spund off the extra PSI as I crash?

 

[day_trippr]

I think I read recently that 5 points is all it takes to carb 5 gallons via spunding, so one point per half-volume of CO2. And you shouldn't gain much carbonation during a cold-crash as presumably the yeast had already finished the job and the beer will only absorb so much from the head space. So the over-carbonation had already happened.

Plot out your temperature from when you close the blow-off and keep your spunding valve set to the temp + pressure=carbonation curve...

Cheers!