Study of living tissues has gained wide spread application in microscopy with the advent of fluorescent dyes and inverted microscopes dedicated to their viewing. A critical component is maintaining physiological conditions in media formulations, including pH and osmolarity, without contributing to background fluorescence. Most cells are grown in media formulations that use bicarbonate buffers, requiring the continuous presence of CO2 to maintain physiological pH. Just 15 minutes outside a CO2 incubator can change the pH from 7.4 to 8.1, and to 8.7 after an hour.