It's true that there's always a balance between CO2, ferts and lighting, but in a low light tank the bottleneck, what biologists call the "limiting factor", is light. Even with low light plants. Low light plants are simply capable of growing more slowly instead of dying when light is low. Adding CO2 will not help because the plants will not be able to use it.
In very, very simplified terms, photosynthesis works like this:
CO2 + light --> sugar
A given amount of CO2 requires a certain amount of light to convert it. If the light is the limiting factor, which it will be in any situation with less than around 2-2.5wpg, then adding CO2 will not help.
Plants are like a difficult child eating cookies and drinking milk. This difficult child will not eat cookies without milk, nor drink milk without cookies. If the child runs out of milk, piling cookies in will not increase her consumption. You'll just end up with a lot of uneaten cookies. And you can't sit plants on the stairs or cut their TV allowance.
In very, very simplified terms, photosynthesis works like this:
CO2 + light --> sugar
A given amount of CO2 requires a certain amount of light to convert it. If the light is the limiting factor, which it will be in any situation with less than around 2-2.5wpg, then adding CO2 will not help.
Plants are like a difficult child eating cookies and drinking milk. This difficult child will not eat cookies without milk, nor drink milk without cookies. If the child runs out of milk, piling cookies in will not increase her consumption. You'll just end up with a lot of uneaten cookies. And you can't sit plants on the stairs or cut their TV allowance.
