You don’t need to take any measures to block even the room lighting. Please observe the aquatic plants and fish after a certain period of time after the aquarium lighting is switched off. You should be able to notice the aquatic plants with closed leaves and fish becoming quiet. You may even witness changes in the fish body color (become less colorful) or patterns. These symptoms indicate that the plants and fish are asleep. For the timing of aeration, CO2 injection should be switched to aeration using air pump or small wave maker when the aquarium lighting goes off. The use of the Dual Socket Control Timer is very convenient as it provides an automatic switch-over function between CO2 injection and aeration according to the ON/OFF Light