how many 2 liter coke bottles of yeast generator CO2 can i use for

[nilesh7318]

I am using (2 liter coke bottle) yeast generator for my 60 us gallons aquarium. my aquarium is medium light tank with easy growing plants. now i want to supplement them with CO2 to help them grow a bit fast.
Can anyone tell me how many 2 liter coke bottles i use for co2 yeast generator.
Thanks.