I am still a novice brewer, so I still need others opinions and experiences. My first 3-4 brews were done w/ cooler temps both w/ water and the air. My finished brews were in the 10-11 ppm of D.O. As the heat and humidity has been rising steadily for about 2 months, finished DO has steadily dropped. The last brew was 8.3. From reading this chart from a soil foodweb link, max DO go down as water temp increases and pressure drops. http://www.soilfoodweb.com/03_about_us/approach_pgs/tbl_6.2.pdf Anyone know how to convert the presure from metric to inches? How long a life will a 8.3 tea have in a tank w/ circulation and a pond air stone w/ a 12 volt air source have? I know the tea is dipping below the 6.? number we like to stay above at the end, but how long would you consider the tea still usefull after going below that number? I guess what I am trying to ask is after hitting the magic temp does the tea go from aerobic to anaerobic instantly or what time frame?