Blowing through an air stone once or even a dozen times isn't going to introduce enough CO2
into the system to make any kind of difference. You could blow through it for the rest of your life and still not.
Your fish were probably just a little scared by something new. I'm sure they will settle down.
Remember, people (like myself) use pure CO2
for planted tanks and have it running 24/7 365 without issue. Granted the plants do use it but even with an non-planted tank you don't have enough pure CO2
in your lungs to make a difference in the water composition.