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Discussion Starter · #3 ·
sells 190w 36" fixtures too!
the question is how equal
is his wattage equivalent
to what you really get.
also how quickly will the
LEDs fade over the years.

only $55 :bounce:

because the light angle is 120°
you probably need to baffle the
sides a bit to reduce the glare.
 

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Only 700 lumens for the fixture though, a T5 54 watt starcoat puts out just shy of 5000 lumens per bulb. So to replace the T5 4*54 fixture you'd need 20,000/700 = roughly 28 fixtures.

It'll be a bit tight since 380 or so LEDs fit in area that looks like its roughly 36 * 2 inches or 72 square inches (I'm only counting the bulb area). My 83 gallon is 48*18 (864 sq inches) so 864/72 = 12 fixtures of surface area available.

The bulbs here are roughly .5 watts each, manufacturers will need to have leds of at least 1 watt or upward and 100% coverage of the canopy to achieve T5 lighting levels. Now, if someone who understands PAR could step in and explain how effective LED light is at meeting plant needs...
 

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If you look at the description of how many watts of light it uses it is very low. The output is probably an equivalent of an incadescent light source. These lights will be very weak not nearly enough to light a fish tank to grow plants. The expensive LED ( solaris) lights list wattage like any other light (watts used). I think those things have 3 watt LEDs in arrays. Individual 3w LED lights have way more output and cost a lot more than the LEDs in this light.
 

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Discussion Starter · #7 ·
just for fun, I'm going to prove all you naysayers wrong :tongue:

this seller has invited me to his showroom to see them
on display. I plan on bringing a 30watt 6500k spiral bulb
and taking a photo of the light from that bulb against
this 80watt LED spotlight at one and two feet from the
same lit surface, then take a no flash photograph.

How else do you suggest I "test" this light to see if
it holds any promise for use in a planted fish tank?
 

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30w spiral bulbs are REALLY inefficient. It's not a very apples-to-apples comparo.

Tommy
 

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This particular test will stongly favor the LED as it is directional and the spiral is not (even with a good reflector there will be restrike). The example in the extreme is the laser: Lots of power in a small area <but not particularly good at lighting a room.>

You might just have to set up two comparison tanks.

this seller has invited me to his showroom to see them
on display. I plan on bringing a 30watt 6500k spiral bulb
and taking a photo of the light from that bulb against
this 80watt LED spotlight at one and two feet from the
same lit surface, then take a no flash photograph.

How else do you suggest I "test" this light to see if
it holds any promise for use in a planted fish tank?
 

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Actually the LEDs available today are in the range of ~30 lm/W. The sprial will do ~62 lm/W with the T5 ~99 lm/W. So LEDs are getting better but, they are not quite there yet.

Edit: 700lm/80W = 8.75 lm/W. (from the details posted above)

Edit2: 300lm/4.5W = 66lm/W (from the ebay posting, better)

30w spiral bulbs are REALLY inefficient. It's not a very apples-to-apples comparo.

Tommy
 

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Actually the LEDs available today are in the range of ~30 lm/W. The sprial will do ~62 lm/W with the T5 ~99 lm/W. So LEDs are getting better but, they are not quite there yet.

Edit: 700lm/80W = 8.75 lm/W. (from the details posted above)
Read the discription though its not 80 watts. Its 4.5 watts. Its marketing. Its just like when the 13w spiral bulbs say equivalent of 60 watts.
 

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Discussion Starter · #12 ·
Read the description though its not 80 watts. Its 4.5 watts. Its marketing. Its just like when the 13w spiral bulbs say equivalent of 60 watts.
thanks man, i know how to read, and all about marketing.
the 30w spiral IS 30 watts, so it's giving about 100 watts
of incandescent equivalent light. so comparing that to
this 80w'like LED array should be interesting.

instead of you guys ranking on me for trying something,
why don't you suggest a fairer test. I could schlepp my
2x65w 8800k Orbit, but would rather not risk it. so the
30w spiral with an aluminum cone reflector will have to
do for now.

i use that 30w spiral & reflector in my 10gal tank photo
 

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Fixed the math above :) I will try and think of a better test... Perhaps the f-stop method as a stand in for a light meter...

instead of you guys ranking on me for trying something,
why don't you suggest a fairer test. I could schlepp my
2x65w 8800k Orbit, but would rather not risk it. so the
30w spiral with an aluminum cone reflector will have to
do for now.

i use that 30w spiral & reflector in my 10gal tank photo
 

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You could use a camera's light meter on a DSLR to compare to any available aquarium fixture. Just set at a low ISO and take notes to see where the aperature or shutter speed says is properly exposed for each fixture. Then compare. Use spot metering for sure.
 

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thanks man, i know how to read, and all about marketing.
the 30w spiral IS 30 watts, so it's giving about 100 watts
of incandescent equivalent light. so comparing that to
this 80w'like LED array should be interesting.

instead of you guys ranking on me for trying something,
why don't you suggest a fairer test. I could schlepp my
2x65w 8800k Orbit, but would rather not risk it. so the
30w spiral with an aluminum cone reflector will have to
do for now.

i use that 30w spiral & reflector in my 10gal tank photo
Obviously my last post was not directed at you. I didn't quote you. Are you sure you can read?
 

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Discussion Starter · #17 ·
Obviously my last post was not directed at you. I didn't quote you. Are you sure you can read?
Thanks again for posting on this thread, ianiwane. you've been a great help so far :icon_roll

guys, I'll see what I can do to use my camera as a light meter, but the feature set on this Nikon 3.2mp camera is some what limited. so I'll probably just end up taking photos of the light being thrown on an object by the two fixtures side by side (not in separate photos) and let you be the judge.
 

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My concern would be the spectral spread of the fixture.
 

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Discussion Starter · #19 ·
My concern would be the spectral spread of the fixture.
could I demonstrate that by shining it's light on a multi colored object that includes most of the visible light spectrum?
I could put a dozen frosted glass marbles under each light and photograph how the colors get represented side by side.

If someone would link me to a color calibration photo I could print that on my ink-jet, and use that as a flat backround.
I found these: http://www.bic.mni.mcgill.ca/~malin/pics/woto_colorcal.jpg http://www.naturalcolorlab.com/graphics/NatLabColorCal.jpg

30wPCF from 18"
6xLED Flashlight from 4"
notice how dark and washed out the red gets.
 

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You'd need a camera that can run in a manual mode and the eV/fstop charts that would tell you how much light you're collected at a given aperture/shutter. Even then, you could have some pretty serious innaccuracy depending on what spectrum the light meter in the camera is optimized for (surely not pure fluorescent).

In my opinion the only test that would mean anything is something that measures lumens, cheers for trying but its not very likely that it'll be accurate or meaningful (sorry!)
 
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