If I crank things up to induce really heavy pearling, I can't sustain that for very long without other issues creeping up. Too much light could produce algae, and too much CO2 will send my Bows to the surface.
So I look at pearling as another one of many things to pay attention to. I don't know how to describe what is the right amount of pearling in my tank, but I know it when I see it. Too little gets my attention, and so does too much.
Curios how others view it?
I don't believe that CO2 and O2 in the water are mutually exclusive. I believe with heightened aeration that high levels of both can be achieved.
I also believe(suspect) that higher lights and CO2 that induce more pearling means that the plants are creating more oxygen. And this can translate to more O2 in the water.
The problem with high/fast CO2 injection is that it necessarily happens before lights go on when the plants have a chance to create oxygen.
If there is little water movement around the plants, the O2 may actually stay "adhered" to the plant leaves and there could be less surface exchange and poor distribution of the O2. IOW, there is more O2 in the tank, but unless there is circulation, it is effectively not released from the plant. So this contributes to "lag" in O2 production. CO2 turns on, O2 begins getting displaced, and O2 may not be available and distributed for another couple hours after lights on.
Since I began using a venturi to inject air to the tank through the night, I have not seen my fish with increased respiration. I can drop the pH 1.5 before lights on and the fish are breathing slowly and relaxed in the morning.
Since the plants are taking O2 from the water when lights are off, if high levels of CO2 is causing respiration issues, I believe the real issue is that O2 was already low when CO2 was turned on, and the rapid pH drop only makes it worse. Its my belief that with excessive aeration through the night, that O2 can be in a high state before CO2 turns on and there won't be any respiration issues.
This problem of morning low O2 from plant consumption is going to be even worse the more growth and plant mass there is. High light and CO2 means more growth, but also that the plants are stealing more O2 from the water at night. I don't think the animals should ever be in a situation where they can't breathe, but I also think its possible to overcome that problem AND still inject high levels of Co2.
Ive tried various methods of aeration. HOB and bubble stone seem to be no comparison to a power head w/ venturi that makes the tank look like a snowstorm. The problem with the venturi is that its pretty horrible for a display tank; you're not going to want it running when lights are on.
To summarize, I believe with exceptional aeration it is possible to run more CO2 without any adverse effects on the fish.