look, I think using pressurized Co2 isn't complex. Let me share my opinion of how to do it.
If you really want to do it right, look at the plants/algae/livestock instead of a drop checker or other means of estimating its concentration.
Just set up the "gas day" so you can be around all day
to observe any changes in the livestock behavior while you crank it up a tiny bit at the time. Given that there is good surface agitation for proper atmospheric gas exchange(aeration), there is nothing to worry at night.
Leave it at the most you can inject without suffocating the livestock, then watch new plant/algae growth in a two week span at least
. Back up a tiny bit every two weeks to be able to observe plant/algae growth. If you are getting stunted plants and more algae, bring it back up a fuzz and that is it.
Now, if you have too much light, beyond the capabilities of plant mass vs CO2 to do the necessary photosynthesis then algae will fill the gap. I never go above 6 hrs.
I hope this helps.
Oh, and by the way, your tank looks awesome but I think it will look even more awesome with background...