So much depends on your breathing rate. For a ballpark exchange of 2 liters, the difference in consumption between a 2.5 second inhale/exhale (5 sec total) and 3 sec each is substantial: 0.85 cuft/min vs 0.7 cuft/min. 4 sec each will hit the average value in the ongoing poll here on SB.
Take a minute to mentally "slow down" and relax before descending. Breath with your diaphragm (aka "belly breathing"). Comfort in the water will also help and usually comes with more experience.
Take a minute to mentally "slow down" and relax before descending. Breath with your diaphragm (aka "belly breathing"). Comfort in the water will also help and usually comes with more experience.