excess co2 is harmful?

so i got my yeast today finally.They are tiny balls tho,i thought it will be like powder,but anyway,it says "active yeast" so it should work rite?So i was thinkin that could i harm the plant if i use too much of it ? and does the reaction start only after shaking it for 2 days?
THanx
grow..

I dont know if too much can harm the plant. I asume so. but you need not worry. yeast wont make too much

cool ....

Youd have to get above 1500 ppm which is optiomol co2 which to even get there you need co2 tanks or co2 generators. 1 2l bottle will only give off the slightest amount of co2 more or less not even affecting the grow. A 5 gallon buckets in a small space maybe a 2x2 by 4 foot area would show some increase in growth.