Confused
NEWT!!! I loved your article man.
Well... Honestly, i have read many articles before and got near about the same info (in bits and pieces) but this thread of yours is really good for those who want to get technical.
And, I hope you can answer my queries cuz i am seriously confused right now as I am planning to start a planted fish tank.
Basically, i am confused on whether to go for for SHO CFL or T2 lights? (LED is out of the question cuz frankly, i am broke)
Or should i just go for T5HO lights?
Also, i have some confusion regarding the Kelvin Rating.
SHO CFL
SHO CFL's are used in hydroponics!!! Like... quite a few people grow radishes and tomatoes and what not under SHO CFL lights.
This is pretty cool to know cuz if you can grow an onion with this then it's pretty reliable
The WPG* rule for a SHO CFL i came across was:
a. 2 to 2.5 wpg for freshwater setup
b. 2.25 to 2.75 wpg for marine setup
*i know the WPG is not to be taken seriously but i take it as a beginner's guideline.
T2
T2's are ultra-thin
The WPG rule for T2 that i came across is:
a. 1 to 1.25 wpg for freshwater setup
b. 1.5 to 1.75 wpg for marine setup
*this seems good for me as i want to minimize the energy i consume cuz i run up hefty electric bills easily :/
T5
T5's are thin. It maybe old technology but is still quite popular & selling.
The WPG rule for T5 i believe is 2-3wpg (although the 2-4wpg was for T8 and 2-5 wpg was for T12. i just dunno why the lower limit is same for all
)
and T5HO being Higher Output lights must be near SHO-CFL's WPG requirement (i am guessing)
Now, whether i select SHO CFL or T2 lights, what's next?
See... i think i have understood why Kelvin Rating OR Lumen per Watt are NOT to be considered solely before deciding on the light.
BUT... i am still confused with the Kelvin Rating part.
To elaborate, say i take a 6500k T5 light without checking other parameters.
I could have easily made a mistake cuz this light may:
1. have weak PUR/PAR output
2. have a dominant green wavelength spike (which the plants don't need)
This would mean that the light is not very efficient (from the plant's perspective, although from our perspective it looks nice & bright)
So basically, a 6500k light should have a good PUR output & have red &/or blue wavelength dominant spikes instead of green wavelength dominant spikes.
(Reason being that underwater plants have evolved to utilize mostly the red & blue light wavelengths rather than the green light wavelength)
Now this leads to a confusion.
A 6500k light is supposed to be white & since it's white, it should technically give out equal quantities of red, green & blue wavelengths.
Right?
Why then do wavelength spikes occur?
Can the wavelength spike alter the color of the 6500k?
If a wavelength spike does alter the color, won't it contradict the concept of Kelvin Rating?
(cuz you know... a 6500k must look white and not greenish or orangish or pinkish or whatever)
After noting the models of available SHO-CFL/T2/T5 lights available in my country, where can i get details such as:
1. Dominant wavelength output graph
2. Wavelength of light system giving (in nm's)
3. PUR/PAR output
--
other sources:
http://www.americanaquariumproducts.com/aquarium_lighting.html
http://www.tropicalfishkeeping.com/...bs-6500k-rating-make-95749/page2/#post1009402
http://www.myfishtank.net/forum/aqu...10-000k-little-lesson-light-temperatures.html
http://science-edu.larc.nasa.gov/EDDOCS/Wavelengths_for_Colors.html
http://en.wikipedia.org/wiki/Color_temperature