I'm confused by WPG.

el wadd

el wadd

Master of the Stupid Question.
Sep 26, 2006
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uranus
I don't get it....

What's the difference in WPG between a standard flourescent and a T-5 HO plant type tube? I have two 54w T-5 HO tubes that came with a Nova Extreme Retrofit kit. It came equipped with one 460nm actinic, and one 10,000k Slimpac tube. I plan on switching to more plant appropriate HO tubes, but am hearing that I still won't have enough WPG to really get my plants going the way I had initially hoped.

Is this true? I can't believe that the HO tubes are the light equivalent of a standard flourescent tube, and fall into the same formula for determining WPG.

What about Lumens? Do they count?

If anyone can help with some info, I'd really appreciate it.
 
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T5HO will be more intense watt per watt compared to a standard bulb like a T12. Meaning 1 54W T5 will be like as intense as 2 40W T12s (well roughly, I dont have specific figures).

WPG is just a rule of thumb, to get you in the ballpark. Bulb effeciencies and reflector differences vary widely. Lumens is a measure of light based on the human sight's sensativity to light. Plant sees light differently so lumens arent the best measurement.

The main advantage of T5 though is because of its skinney profile it can put a lot more of its light in the tank when matched with a good reflector. I'm not familiar with your fixture, does each light have its own multi-faceted or parabolic reflector? Or does it simply use a flat reflector that all the bulbs share? You'll loose a little bit if its a flat reflector.
 
it's a 5 sided reflector with a flat bottom.
 
loaches r cool said:
T5HO will be more intense watt per watt compared to a standard bulb like a T12. Meaning 1 54W T5 will be like as intense as 2 40W T12s (well roughly, I dont have specific figures).

WPG is just a rule of thumb, to get you in the ballpark. Bulb effeciencies and reflector differences vary widely. Lumens is a measure of light based on the human sight's sensativity to light. Plant sees light differently so lumens arent the best measurement.

The main advantage of T5 though is because of its skinney profile it can put a lot more of its light in the tank when matched with a good reflector. I'm not familiar with your fixture, does each light have its own multi-faceted or parabolic reflector? Or does it simply use a flat reflector that all the bulbs share? You'll loose a little bit if its a flat reflector.
Click to expand...

CRI or Colour Rendering Index is the spec you wanna look for, for plants.
Higher CRI = better for plants.

also taking into consideration the spectrum requirements for your plants.
 
Umm...

Color rendering index (CRI)
The color rendering index identifies the degree of color shift objects undergo when illuminated by a particular light source. In simpler terms, the CRI expresses the degree to which a light source renders the true color impression. The CRI is an index and ranges from 0 to 100. A light source having a CRI of 100 means objects illuminated by it look like they're supposed to; that is their natural color is not distorted. A light source having a very low CRI would tend to make objects appear to be a different shade or even color that they really are.
Click to expand...

from http://www.geocities.com/CapeCanaveral/4742/lighting.html which is an excellent article on lighting for tanks.
 
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