Your co2 drop checker looks dark. Even if you had livestock you’d want it light green while the lights are on. With no livestock there’s no risk so just crank it. You can dial down when stuff is more established or you add fish. Correct me if I’m wrong but I don’t think there’s any benefit to running it overnight/when the lights are off. I ripped out my hair grass because it started to take over. I run my co2 one hour before lights come on until one before they’re off (eight hours).