The goal is to have the same concentration of CO2 in the water every day, while the lights are on, not to have it the same 24 hours a day. The green drop checker just means you are in the right ballpark for CO2 -you have 10-45 ppm, not 2-5 ppm - so you still need to adjust the bubble rate to get to the optimum bubble rate. You can do this by slightly increasing the bubble rate, then watch the fish for distress, and watch the plants to see if they grow better, more pearling, etc. Watch for a few days. If the plants do better, repeat this until either the fish are distressed, or the plants don't do any better, then back off to the last bubble rate. You need to have good oxygen concentration in the water for this to work well, so you need the water surface rippled all over, but no splashing. Using a wet/dry filter will give you the most dissolved oxygen.