My 240l fairly heavily planted tank is going wild. Everything is growing well and in need of trimming. It’s a low light setup (well I think so anyway) and even my rotala orange juice is growing and has the orange tops. At what point would co2 injection become required. Is there a sign to look for that the plants are needing extra co2. I was using flourish excel but I have ottos, shrimp and a L134 and although I supplement their diet with courgett, I need some algae in the tank.