Dissolved Oxygen (DO)

1. Dissolved oxygen is a measure of the total amount of oxygen dissolved into fluid, measured and displayed in parts per million (ppm) every 10 minutes. As the readings approach a 1.5 ppm detection limit, they become too low to detect and can be considered 0.
   
2. The primary benefit of reading O2 in this manner is as an early indicator (within 10 hours of pitching yeast) to ensure that healthy yeast is uptaking oxygen during the lag phase but before other signs of fermentation are detectable. Common fermentations show that O2 levels should drop below the detectable threshold within this time frame.
   

Pressure

1. Precision Fermentation is actively evaluating the correlation between gravity measurement and conductivity. Although gravity readings may fluctuate during extremely active fermentation, it also tends to coincide with extremely volatile conductivity measurements.
   
2. Both gravity and conductivity are directly impacted by the presence of gas in the solution.
   
1. In the case of conductivity, gas is not conductive, therefore the rapid rise in the presence of CO2 creates a drop and extreme volatility in measurement. And, the initial gravity drop coincides with a drop in conductivity followed by extreme volatility until gas production begins to slow.
   
3. As fermentation slows, producing less C02 in solution, gravity measurements return and conductivity rises and becomes much more stable.
   
4. Conclusion: If gravity measurements start to scatter or start to gap, take a look at conductivity. If the initial drop in conductivity is followed by volatility in gravity measurement, it’s a good sign that your fermentation is extremely active at this time.