Originally Posted by pjcvijay
Do I need CO2 unlike Walstad method? Thanks!
The need for CO2 is caused by having a lot of light, not from using a soil substrate underlayer. When plants are growing slowly they don't need a lot of carbon to use to make new plant tissue. The faster they grow the more they need additional CO2 for the carbon. And, the biggest cause of fast plant growth is ample light. If you ignore this need for more carbon the plants will not be very healthy, and unhealthy plants invite algae to take over.