What volume of Co2 during fermentation?

[drathbone]

I've made a few batches of EdWorts apfelwein - 5 gals store bought apple juice, 2-3 lbs of sugar (3 lbs in most recent batch) and using Red Star Montrechet yeast.

After ~4 weeks of fermentation, the product is still foamy/lightly carbonated straight from the carboy, as I assume it's still fermenting. Is there a way to know what volume of Co2 this is? It's the perfect level and I'd like to maintain it when I choose to bottle/keg.

Around the 8 weeks mark is when all the Co2 seems to be out of solution while sitting in primary and the mouth feel is too watery and not nearly as palatable.

 

[bucketnative]

For a beer or cider that has just finished fermenting, there will be about 0.8 to 1.0 vol CO2. At 18°C, the saturation point of CO2 is roughly 0.9 vol. You can reasonably assume that it will be close to saturated (that's the assumption that the online calculators employ). During active feremantation it may be slightly supersaturated due to back pressure from the fermenter.

FYI - The EU mandates that still wine has less than 2 g/L CO2, which equates to 1.0 vol CO2. Above that it ventures into semi-sparkling, and then further into sparkling territory (>6 g/L). Supposedly the CO2 is perceived as light effervescence from 1 g/L and up.

 

[Yooper]

It's not still fermenting, but there is some dissolved c02 still in solution since the cider is under an airlock.