Sounds like the tank never degassed much CO2 at night and thus you can also state that the tank also did not have much transfer of O2 INTO the aquarium either.
That's not the best management for fish.
The CO2 is only added during the light periods. No reason to have it or have it hang around otherwise. You had very little degassing.
If you add a bit more, again, so what? You gain a much better environment for fish and the plants.
Seems you should max the O2 1st................then add enough CO2 to target a good CO2 rate.
If you aggressively break the water surface, then it's very hard for the CO2 addition without losing it asap.
But you also do not GAIN any added O2 from going that aggressive with the current, there's a trade off here.
If you add just enough current to NOT break the surface, then you strike optimal O2 and then good CO2 management.
Not all tanks will do poorly without such current.........and if you use a wet/dry filter, surface skimming, then you gain more O2 and have less need to have surface movement.
My 70 Gallon is like that, it's mostly a "still" surface.
The 180, not so much, nor the 120.
Some folks only have a few fish, then it's less of an issue also.
But I think it's overstated about having people minimize the water movement to save CO2. We waste most of the gas anyway to the degassing.
Low O2 also causes many aquarist to claim they cannot add more CO2 without gassing their fish. Their tank's issue is not the CO2, it's the low O2 they have.
Respiration is both CO2 and O2.
So max the O2 where adding more current not longer helps/increases O2, then add CO2, that will give you the best overall management and widest user flexibility over a CO2 dosing rate.
This can help aquarist much better than suggesting little surface movement to save a small amount of CO2. That's easy to add a little more to compensate.