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MikeJones
06-14-2006, 05:19 PM
Has anyone else heard or noticed that if you run enough lights then you don't really need co2. I say this because a friend of mine is running 2 600 watt digitals per 4x4 tray, which is like 75 wpsf, and cut the co2 in one of his rooms and saw no difference in the two. When I say no difference...I mean no difference...growth rate, DENSITY,...nothing. I wonder if this is just him who's getting these results or if other people are having similar results. I run 60 wpsf and I couldn't imagine not running co2. To me it seems absolutely necessary.

David G.
06-14-2006, 10:40 PM
I suspect that the CO2 levels in room B (the CO2 enriched room) are not where they should be. Let me explain why.

Plants take light and CO2 and process them (through photosynthesis) in order to manufacture food for themselves. If you think about it, CO2 and light are the "real" food that plants require, much more so than nutrients and enhancers. Nutrients and enhancers act as more of a catalyst then food - if these elements weren't present, then photosynthesis would not be able to take place. If you took a head of lettuce and had it analyzed, you would find that it contained over 90% water, somewhere around 6% carbon, and the tiny remainder would be minerals. That means that the dry weight of the plant is mostly carbon. So, carbon (CO2) and light are like the big steak you have for dinner, and all of the nutrients and enhancers we growers like to put so much emphasis on are roughly equivalent to the salt and pepper we season it with. Kind of puts things in perspective, doesn't it?

There are many factors associated with growing a plant and achieving the fastest growth rate and the highest yield possible. As I just explained, light and CO2 are paramount. Yet, there will always exist a "weak link" in the chain of factors, meaning that although you may have plenty of some factors (such as light and the proper nutrient levels), there will be one factor that isn't being fully met (possibly CO2 or temperature) that keeps the plants from being able to fully utilize the other factors. A common example is a grow room with CO2 levels in excess of 2,000 ppm, but light levels barely equivalent to an overcast day in winter. The grower is wondering why his plants aren't taking off with the huge amount of CO2 he is giving them, but in reality the plants aren't going to benefit from the huge amount of CO2 (2,000 is at the top of the scale as far as what most plants can process) unless they have a huge amount of light, perfect nutrient levels, etc. Bottom line: your plants will only grow as fast as the weakest link permits.

And now, back to our original point. If both grow rooms had above average (or perhaps even adequate) lighting, nutrient levels, temperature, humidity, etc., and room A had only ambient CO2 levels (300-500 ppm), and room B really did have higher CO2 levels, then one would have to assume that room B would be doing noticeably better than room A.

Geez, that was a long-winded explanation, even for me! :D