Originally Posted by fishstick41
soo when will i know if i need co2? jwing
thanks guys for yalls comments
The short answer is, you won't need added CO2. But I must explain.
Plants need 17 nutrients to photosynthesize (grow), and carbon is one of those, but it is a critical one. The extent of the plants' growth will depend upon a balance with light and the 17 nutrients. Plants have little control over photosynthesis, they will do it to the max as long as what they need--the light and nutrients--are available. When any one of these is no longer available, growth will slow or may stop--until such time as everything is again available. We term this the limiting factor.
Creating the balance is not really difficult, but the first question an aquarist must answer is to determine what level of growth they want. If light and nutrients are low (minimal) but still balanced, the plants will grow slowly, but they will be healthy. If you want faster growth for some specific reason, light and nutrients must be increased--but still balanced together.
There is a lot more CO2 in the average aquarium than many realize. Fish and bacteria produce CO2 continually, day and night, and the bacteria produce more than the fish. During daylight, plants will use the CO2, provided the other nutrients are available and light is adequate. Increasing the light alone, or the CO2 alone, will have very little effect on improving plant growth and may cause terrible algae problems. Algae is a plant, but one that is able to use any light (unlike plants that need red and blue to photosynthesize) and it can take advantage of shortages in nutrients that would prevent plants from growing.
Many of us here are advocates of what we term natural or low-tech planted aquaria. Light is minimal, and nutrients are the same to balance. For most of us, in fact i would go so far as to say all of us, there is adequate CO2 in the aquarium to balance the minimal light and other nutrients. Our plants grow, perhaps slowly but not always; I have quite remarkable growth from my swords with a very low-tech method.
Hope that explains it a bit.