so yer saying that tubes will always be more light efficient because the light leaves the lamp better?
If all other parameters are equal.... then yes.
...sorry for the noob Question but describe lumens vs, Kelvin. lumens is the amount of light given and kelvin is a quality of the light then correct?
Lumen is probably the single most abused term in describing plant lighting.
Lumen is a measurement of the amount of energy that is emitted by a source, but is limited to the energy that is visible to the human eye. So I can have a very high lumen source that doesn't grow squat, or I can have a low lumen source that grows plants well.
Seedjar is spot on about Kelvin, it is a reference to the temperature (in kelvin) that a black body would have to be heated to in order to produce the same color of light.
Typically the higher the number, the more bluish the light source will appear. The lower, the more red.
IIRC, During the normal daylight cycle, this varies form somewhere around 3000k to 6500k, with noon being about 5000k
The most commonly used kelvin range for plant growth is 4100k to 6500K
CRI is color rendering index, this is a measurement of how accurate the colors will appear. A rating of 100 is the highest possible. Typically the higher the number the more "broadband" the light source is.
...i understand what you mean about the crazy amount of variables but am I missing anything is what I'm asking i guess
This is subjective.... are your plants healthy?... are they producing good color/dew/etc?...are you happy with their growth and appearance?
Can you have better, well of course... there is always room for improvement. But a lot depends on what is the limiting factor. The amount of light you can use depends on other variables... nutrient levels, CO2 levels, species etc etc etc.
Be aware that there are not black/white answers to this stuff.... If you are not happy with your results, try another bulb. Give a 5000k or 4100k a try. You can also move bulbs closer if possible, energy levels vary based upon the inverse square law.
One of the most overlooked but important variables is reflector design. Even with linear bulbs over half the bulb is pointed in the wrong direction. I'd rather have a T12 with a good reflector as a T5 with no reflector.
and not all bulbs are created equal, while most will grow plants.... there can be a signicant difference between two bulbs having the same Kelvin temp.
FWIW, the GE's are suppose the be some of the best of the CFL
HTH's
Av