Is this true?

[strayner]

"Most plants can grow under all 3 light conditions if CO2 is not the limiting factor. For example it is believed that Hemianthus calitrichoides Cuba (HC) needs high lights to be able to grow into a foreground carpet. This isn’t true! This plant will do just fine under lower light conditions as soon as the CO2 is not a limiting nutrient. In CO2 limited systems HC like many other plants will grow upwards trying to reach over the water surface where the atmospheric CO2 is available. Many believe that plants grow towards the surface to get closer to the light source which isn’t true. The most common reason behind plants growing like this or simply melting away is due to the limiting CO2 factor.Of course under low lights plants will grow slower but with good CO2 levels they will eventually grow into the desired aqua-scape."

Has anyone been able to test this? I am suspicious of this claim.

[jvision]

I've grown thick carpets of E. tennelus (Pygmy Chain Sword) with just around 2wpg of T12 lighting on a 2' deep tank... so that claim could be true; but, I've never really thought E. tennelus was a high-light plant, tho.

[strayner]

And i've got E. tenellus surviving at 1.6 wpg right now! haha.

[AvianAquatics]

Maybe. I have HC at over 4WPG and they would grow some and die some so I never really formed a "true" carpet. Now I've added CO2 and found they are growing a lot more quickly and the dying areas have not really spread. But still, it pays to have both high light AND Co2.

[Kronosdelsol]

I don't agree with the statement.

I had HC growing on low light (T12) without co2. It just grew straight up as you had mentioned. When I switched to high light, it grew low to the substrate. Using injected co2, makes it grow faster obviously.

I don't think providing optimal co2 is mandatory for any plant growth, as long as your plants have adapted to the co2 levels in your environment. Most plants that come from the store die off within several weeks because it hadn't acclimatized to the lack of co2. Once it has acclimatized though, it will still grow regardless of low light or high light. It will just take its time.

[werner]

CO₂would not be the only factor involved, as the quote seems to indicate.

Besides light quantity, light quality would have some bearing on the growth as well:

-water that is high in organics/tannins will prevent wavelengths from penetrating to the bottom as easily.

-blue wavelengths are supposed to encourage more compact growth.

-red light encourages taller growth.

Many plants head for the surface in order to flower. <---kind of an important plant priority.

Just wondering where the quote is taken from?