Originally Posted by Joshstraps
Is the co2
to replace what the light pulls out of the water?
No. plants need CO2
for cell growth.
Using the 2.5 WPG
rule as a basis, you don't need to run CO2
unless the plants demand it. Typically, the more light at the right spectrum you have going into the tank, the more CO2
and ferts (macro and micro) you need to dose to keep your plants healthy and stave off algae. The key is to find the right balance that works for your tank when it comes to lighting.
Correspondingly, the less light, the less necessary it is to dose CO2
. Remember that some is already dissolved at the tap, as well as from fish respiration and gas/atmosphere exchange at the surface.