yeah i have plants so i turn on the air pump once a day to break up that sticky film on top.
well I was thinking about these 3 things:
1. how during photo synthesis absorbs CO2 and releases O2 but when theres no light the plants start releasing CO2 back into the system
True: reverse respiration I think but not for all plants if memory serves. I would be more concerned with CO2 produced by the fishes/accumulating during the night.
2. CO2 only reaches the same amount as in the atmosphere due to gas exchange
Reaching Equilibrium takes time depending on the physical condition, etc, etc.
3. someone said the film layer prevents gas exchange
so yeah when I turn on the airpump, its gonna make lots of bubbles and break up that film on top and start causing lots of gas exchange and idk... do stuff
True but should not let film develop on top as other gases have to exchange as well. Let filter break up the film and remove. You may need to perform small but more frequent wc than what you are providing now.
Actual testing [O2], [CO2] at different time/condition can reveal more about how much O2 is produced by the plants or reversed , etc. etc.
Is there some certain time of the day I should turn on my airpump as to maximize the amount of CO2 thats in my tank
I would only turn on aeration if and only if tank is overstock with fishes where [CO2] may reach lethal level for some if not for all during dark period. If fishes are hanging near surface during middle of the night, would run air pump sporadically thru out the night but not near when light are to be turned on. I would never run aeration in planted tank, especially one with CO2 injection during daytime..