Re: low light and CO2

[Thomas Barr <tcbiii at earthlink_net>]

> I'm here.<g>  And although it's true, I didn't write it.<g>  Claus
> Christensen and Ole Pedersen did the research.  You can read the full
> results in back isses of TAG, PAM, or on the Tropica web site.

Well... independent verification is nice:) I've said this in past also.
 
> The short of it is that CO2 is even more important under marginal light
> conditions.
> 
> Karen

I can confirm this and have nagged that it is true.

I can also say that the results of using CO2 at 1-2 watt/gal range, as long
as the light is well spread out over the area(eg not just a narrow bright
strip of light in the rear of the tank etc), you can have awesome tanks.

The results are better than the non CO2 style tanks where folks don't have
to clean the glass for months at a time.

The nutrient water column levels can also be maintained at the same high
levels in the higher light tanks ....BUT.....uptake is slower.

So where you dosed 3x a week, you may only need to dose once a week. This is
great since you can do your once a week water change and add the nutrients,
then not mess with it till the next water change. Just feed fish etc.

Many plants look very nice under low light.
You spend less on electric.
You spend less on initial purchase of the lighting.
Many plants that are trouble keeping looking good when growing at high
growth rates have the time to assimilate the nutrients into their tissue.

Weekly trimming are now once or twice a month.
Some plants have fuller larger leaves, better colors.
Herbivores are more effective per unit critter since the algae growth is
slower.
Green water and some other species of algae seldom grow.

If you run out of a nutrient, it is far less critical to add it back on
time. Dosing routines are much more flexible but...........
Those recommended nutrient levels Steve and I came up with a few years ago
also apply here for optimum growth, BUT.......the frequency of the dosings
is perhaps only 1-2x a week at most.

The high light tank was able to tease apart what nutrient levels were
critical at very fast growth. Applying that to lower lighting, this gives
the optimum nutrient levels and ratios allowing for better growth, less
algae and more flexibility in dosing.

So ultimately, you don't have to have CO2, but it sure helps a great deal at
low light.

Regards, 
Tom Barr