Respiration and photosynthesis both occur during the day. However, at night only respiration occurs which consumes oxygen. This is what causes oxygen levels to decrease throughout the night. During the daytime even though both reactions are occurring, there is a tendency for a surplus of oxygen to be produced. A cloudy day will be an exemption because there is little to no sunlight.
Carbon dioxide acts like an acid in water.
Carbon dioxide is used during photosynthesis. When photosynthesis is occurring, pH has a tendency to increase during daylight. The use of brand names in this publication does not imply endorsement of the products or services named or criticism of similar ones not mentioned. Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age, or disability.