The bulbs are 16.5 inches long. As I said above, you would get about 70% of the PAR that a single T5HO bulb would give, and the T5HO would be 24 inches long, so it would cover the whole substrate better. I use one of the 36 watt AHS kits over a 15H tank, which is 20 inches long. I get about 30 micromols of PAR with the light 23 inches from the substrate, and it is uniform over the entire substrate. If the light were 16 inches from the substrate I would get about 70 micromols. If the tank were 24 inches long, the intensity might drop a little at the ends of the tank, but not by much, with the light 23 inches high. It would drop more with it at 16 inches, however, if you keep the inside and outside of the glass sides and ends of the tank very clean, you get much better uniformity because of reflection off the glass.
Comparison of Lighting Types (Lumens and Watts)
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Found this today, and thought it might be worth sharing as a graphic representation of what's already been said:
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Originally found at http://4.bp.blogspot.com/_VyTCyizqrHs/TH0gG7EVVMI/AAAAAAAAI3s/wek0ogJNf_U/s1600/lumensperwatt2.gif.
Note that:
1) This describes only lumens (brightness as seen by the human eye) produced in all directions.
2) It doesn't address PAR (brightness as "seen" by plants), although lumens and PAR are at least loosely correlated in most cases.
3) It doesn't address reflectors. Lights typically radiate in all directions, and we need to redirect that into a narrow beam. Some light is inevitably lost in the process. Lights like linear T5's end up being more efficient in aquarium use because they have shaped and mirrored reflectors available which lose little light. Other lights are harder to design efficient reflectors for. LEDs are a unique case, they don't need reflectors since they already radiate in a narrow beam; so no light is lost at all.
4) I'm not sure how old this chart is, so it may not represent recent advances in LED lighting. LED efficiency continues to improve. Efficiencies as high as 135 lumens/watt have been reached for white LEDs in the lab, as documented here; which meets or exceeds the efficiency of all other lighting types even before considering the advantage of LEDs not needing reflectors. We'll probably all be using LEDs in 10-20 years.
Originally found at http://4.bp.blogspot.com/_VyTCyizqrHs/TH0gG7EVVMI/AAAAAAAAI3s/wek0ogJNf_U/s1600/lumensperwatt2.gif.
Note that:
1) This describes only lumens (brightness as seen by the human eye) produced in all directions.
2) It doesn't address PAR (brightness as "seen" by plants), although lumens and PAR are at least loosely correlated in most cases.
3) It doesn't address reflectors. Lights typically radiate in all directions, and we need to redirect that into a narrow beam. Some light is inevitably lost in the process. Lights like linear T5's end up being more efficient in aquarium use because they have shaped and mirrored reflectors available which lose little light. Other lights are harder to design efficient reflectors for. LEDs are a unique case, they don't need reflectors since they already radiate in a narrow beam; so no light is lost at all.
4) I'm not sure how old this chart is, so it may not represent recent advances in LED lighting. LED efficiency continues to improve. Efficiencies as high as 135 lumens/watt have been reached for white LEDs in the lab, as documented here; which meets or exceeds the efficiency of all other lighting types even before considering the advantage of LEDs not needing reflectors. We'll probably all be using LEDs in 10-20 years.
I might be stupid ?
I dont get this at all !
Ive got 3 40w About 44 inch fluorescent tubes each with there own light spectrum in my 120 gallon tank ie
1 blue
1 white
1 red
will i Calculate it 40watt x 3 divided by 120gal = 1wat per gallon ?
Thats not my real problem i think my light is much more than that since I have more area of Light?
I dont get this at all !
Ive got 3 40w About 44 inch fluorescent tubes each with there own light spectrum in my 120 gallon tank ie
1 blue
1 white
1 red
will i Calculate it 40watt x 3 divided by 120gal = 1wat per gallon ?
Thats not my real problem i think my light is much more than that since I have more area of Light?
41 - 45 of 45 Posts
