Yeah, I'm not trying to say damage would be done in such a short period, just that I remember excessive levels could be an issue
This isn't an issue for us. These studies are dealing with the constant and continuous day in day out supplementation of CO2 out over a long period of time.
The way we do it, bombing a tank once per day with CO2 for a few days in a row would not in any way be a problem for our tanks. If we were supplementing continuously at high levels like they might do in a green house where they are trying to stimulate plant growth, then the high levels could be an issue. When I use my CO2 generator, I am dosing the tank once per day where I purge all oxygen, then let it sit over night, bomb it again once the next day, then let the plants respire and absorb the CO2, and if I'm feeling really anal, I might gas it one last time for good measure.
Green houses may be supplementing CO2 on a continuous bases indefinitely. Done this way the high level could be a problem. But then done this way, we couldn't ever put our frogs back into the tank either.
So, there really is no comparison here, nor is there an issue for us bombing the tank once or twice a day for a few days running. I hope you understand that we are talking apples and oranges here.