Does liquid CO2 replace pressurized CO2 gas?
While liquid carbon is often marketed as a source of carbon, most planted tank experts agree that it is a poor replacement for CO2 gas. In reality, many aquatic plants prefer to grow with their leaves out of water because it is easier and faster to directly access CO2 from the air. Therefore, people set up high tech tanks to help their underwater plants by injecting more CO2 gas into the water at concentrations ranging from 10-30 ppm. Some initial studies have analyzed how much is CO2 released from recommended doses of liquid carbon, and the numbers were significantly lower than pressurized CO2. In fact, a normal aquarium with good surface agitation and gas exchange using an air stone or filter results in approximately 3-5 ppm CO2 in the water, which is still higher than what liquid carbon appears to supply.
For more information on liquid carbon and its uses, read our full article here.