Join Date: Oct 2008
Location: Baltimore, Maryland
CO2 is measured in ppm (parts per million), and to know how much of it you need- we'd need to know more about your water chemistry. Test for pH and KH, and tell us what you have. There is a "target" CO2 level, which is proportional to pH and KH. This will get you in the ballpark, anyways. From there, we can determine how it should be distributed (diffused) so that your target CO2 levels are met.
Adding CO2 is one thing- adding the proper amount is quite another. You want to add the proper amount. Anyone can make bubbles, but if you don't know how much, or how it affects your water chemistry- you're shooting in the dark. Compared to algae, plants are more complex and their growth (health) is dependent on certain factors, which when met in the right proportions, sustain health and offer excellent growth rates. When any of these factors are out of proportion with the others- you get problems...lots and lots of problems. Not only are the plants stunted, algae often takes hold. Since algae is a highly adaptive, simple life form, it can thrive on these imbalances. Introducing a syncopated level of CO2 is just inviting it to take over. Disease often finds a way in under these imbalances, too.
So, the short version is: measure your pH and KH before doing anything else. It's very important (if not crucial) to knowing how much CO2 to add. Alternatively, you can choose your desired pH level, and adjust KH/CO2 to reach it.