Normally an erlenmeyer conical flask will be in a shaking shaker environment when used for cell culture. Too much space may cause the liquid splashing to the bottle mouth when shaking, increasing the risk of contamination, and compress the space for gas inside the bottle, which is bad for gas exchange during culturing. Too little working space may make the bottle medium liquid depth is insufficient, reducing the three-dimensional growth space of bacteria and cells.
For erlenmeyer conical flask under 3L, we recommend the best working volume no more than the 30%-40% of the flask maximum volume.