The increased volume in the carboy allows a lot less light to get through, hence looking darker, especially when the yeast drop out. My Kolsch I just bottled looked deep amber/copper colored in the carboy, but in reality is only about 4 SRM.
Originally Posted by onetoeddogbrewery
Been drinking there weak ass qhrumphish ABV beers all day on an empty stomach and still don't have a decent buzz.
In Bottles: Session Beers
In Fermenters: More Session Beers
Planned: Even More Session Beers
I think the color change in the carboy is from the yeast dropping out. Lots of my pale ales are tan in the carboy while fermenting then the carboy gets dark after the yeasts flocculate. The yeast cells are white and they lighten the color even with the large volume in a carboy.
PS. as mentioned above a hydrometer sample will appear much lighter. Even light beers look brown in the carboy.