In Favia species, Kuhl et al (1995) found photosynthesis at incident sunlight to be approximately 10 nmol of oxygen per cm3 per second. The highest rate of gross photosynthesis occurs at the skeletal ridge of the coral, or approximately 1 to 2 mm distance from the coral mouth. Photosynthesis was measured with dissolved oxygen sensors, also known as Clarke-type microsensors (http://www.edaphic.com.au/oxygen/dissolved-oxygen-sensors-and-meters/).