Co2 to Light ratio???

[moe_1]

Is there a required ammount of light to Carbon Dioxide, or vise versa???(planted tank, of course)

Just wondering...

 

[Bol]

Not that I've heard of.

Most plant enthusiasts will agree that the optimal CO2 level in water is 20ppm or so (chances are, 'naturally' it's 3-4ppm).

However, many don't think injecting CO2 is worthwhile unless your light level is roughly 2 watts per gallon (fluorescent) or higher. Opinions vary widely, though.

 

[Lateral Line]

>>> Not that I've heard of.

No, me neither. I read this question yesterday and started to try to calculate something, but the maths gets quite heavy quite quickly. The take up of CO2 depends on the enzyme type of the plant, the light intensity on the leaf, (which is a function of the power of the lights, the depth of the water, and the absorbtion coefficients at the various required wavelengths), and the availibility of other nutrients. Assuming "enough" nutrient and an average figure for enzyme activity, these two reduce to constants which can be factored out.

That still leaves two variables and as it was working out, keeping one constant the other showed an inverse exponential growth, in that from a fixed start point, a little more made a big difference, a little more, not so big, a little more, even less until a level was reached where no amount of extra light, or CO2 alone changed the rates. However, the effect of increasing both seemed to be greater then the sum of increasing either one alone.

I may play around with this a bit more when my headache has gone!

 

[guppygirly]

Do they make test kits/strips to measure CO2?

 

[Bol]

I've seen CO2 test kits in stores, but from what I gather, most people just derive the CO2 concentration from the KH and pH of the water, using:

CO2 (in ppm) = 3*KH (in degrees) * 10^(7-pH)

That formula does not work, however, if significant amounts of non-carbonate buffers are present in the water (namely, phosphates).