Why does plantedtank not bubbleing anymore

The amount of light and CO2 injection volume influence the photosynthesis of aquatic plants. Photosynthesis is not generated if either one of them is insufficient. The amount of light is not a big issue because everyone can get equally adequate amounts of light just by installing a lighting system that is appropriate for the aquarium tank size. On the other hand, the CO2 injection volume needs to be adjusted according to the type and volume of aquatic plants in the aquarium. In view of these facts, lack of CO2 is considered to be the cause of this problem. To solve this, install a Drop Checker, which indicates if the CO2 injection volume is adequate or not by color change, in order to adjust the CO2 injection volume to the adequate level. For your reference, the CO2 injection volume is considered adequate if the pH indicator turns a color indicating acidic (0.2 to 0.4) a while after the CO2 is injected.
Photo (Top): Oxygen bubbles from aquatic plants are evidence of an adequate amount of light and CO2 injection volume.