I assumed the default 8 cm² was fine. It wasn't. My Quercus leaves were 12 cm², and the cuvette window was partially blocked by the midrib. The manual dedicates an entire table to calculating when using gaskets.
Here’s the gem from the manual: When you change CO2 or humidity, the chamber takes time to equilibrate. The GFS-3000 is fast (1-2 seconds for gas exchange, ~5 seconds for the chamber), but if you log data during the washout, you are logging air from the previous condition. gfs-3000 manual
My first instinct? Skip the manual. Big mistake. I assumed the default 8 cm² was fine