An t-iasg has given you a link to the site that most of us used when setting up our first DIY CO2
setup. Do keep in mind that the article is a few years old and therefore the recommended target for CO2
levels is lower than what most of us recommend. To achieve 30ppm of CO2
in a 55 gallon aquarium you'd be looking at about six
2-Liter bottles or three
1-Gallon bottles. Getting good relatively steady levels of CO2
in a 55 gallon with DIY CO2
while possible is usually an absolute pain. With that size tank I'd say that you're better off sticking with your current setup or making the leap to pressurized.
If you do decide to give DIY a try, then you could always use your filter to diffuse the CO2
. Just feed the CO2
line into the filter intake and let the impeller chop up the bubbles. This does tend to be noisier and will shorten the life of some of your filter parts, but is a very inexpensive and fairly efficient means of diffusion.