Should my refugium lighting be opposite to my main tanks lights?
It can be, the reason for this is to help off-set the changes in pH that occur in the main tank during the day/night cycle…. When the Coral and Algae in the main tank are exposed to light, oxygen is produced as a byproduct of the photosynthesis process and carbon dioxide is consumed, this removal of carbon dioxide from the water causes the pH to rise. So when coral and algae are not exposed to light the production of oxygen is reduced and the production of carbon dioxide is increased, which leads to a decrease of pH during the periods of darkness. These fluctuations can be eliminated to a great extent by lighting a refugium in an opposite cycle to the main tanks, minimising the pH fluctuations and maintaining the amount of dissolved oxygen constant in the water.
