# Need to find LED & fluorescent lights with same lumen value, for science experiment



## Morainy (Apr 21, 2010)

*Need to find LED & fluorescent lights with same lumen value, for science experiment*

One of my sons is going to do a class experiment (not a full-fledged science fair experiment, but more of a class project) comparing the growth of aquatic plants in the same conditions under LED versus fluorescent lights.

He's probably going to use nano tanks and donate them to the school afterwards.

Therefore, he needs to use 2 lights that have the same lumen value. Can anyone suggest 2 small lights, one LED and one fluorescent, that would be comparable?

We already have the 13 watt Fluval Ebi light, and a Dymax IQ 3 nano tank LED light (don't know how many lumens), and a workshop light that we could put any screw-type fluorescent twisty bulb into.

How can I find the lumen value of small LED lights?


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## SeaHorse_Fanatic (Apr 22, 2010)

I don't know if a photographer's light meter would work for comparing lumens. I know my DSLR has a built-in light meter but I doubt that would be "scientifically acceptable" for this type of experiment.


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## Morainy (Apr 21, 2010)

Hmm, good ideas! 
This is a class project, not a full-fledged science project, so he can make do with the manufacturer's stated capabilities of the bulbs. But, while we can find information for some of the big, expensive lights and for some brands of screw-in bulbs, we can't find anything for the easy-to-find lights that come with nano tanks: the Spec, Ebi, Dymaz IQ3, etc.


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## SeaHorse_Fanatic (Apr 22, 2010)

Email the manufacturer and explain your situation.


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## neven (May 15, 2010)

Morainy, with screw in cfls, the ones that say equal to 60 watt incadensent are using lumens as the measurement. So even if you can't find your brands data, the lumens should be very close to other brands. Remember though to use the incandesent rating, not the bulb wattage, since they efficiency wise. Ie. 13 watt bulb will be equal to some brands 11 watt bulbs, but both are 60 watts incandescent equivalents


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## Morainy (Apr 21, 2010)

Hi Neven

Thank you! ... Maybe my son should use one of the new screw-in LED lights that are available at London Drugs or Best Buy, that look like old-fashioned incandescents, then, rather than an LED light made for an aquarium? Sometimes the aquarium lights don't give their value in watts or lumens, but the ones made for household use always do. Hmm... thank you!



neven said:


> Morainy, with screw in cfls, the ones that say equal to 60 watt incadensent are using lumens as the measurement. So even if you can't find your brands data, the lumens should be very close to other brands. Remember though to use the incandesent rating, not the bulb wattage, since they efficiency wise. Ie. 13 watt bulb will be equal to some brands 11 watt bulbs, but both are 60 watts incandescent equivalents


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## neven (May 15, 2010)

NP, phillips i think is making the push for the new lighting. They normally will have data available for their lighting if its not on the package. Just remember to have both bulbs facing downwards to make the results more accurate. Twister CFLs have greater restrike sideways compared to vertical, what this means in simple speak, Less light output when sideways. if you are simple desk lamps, or clamp ons from walmart, you should use double sided tape and strips of tinfoil to direct the light more into the tank, since LEDs are very directional.


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## Morainy (Apr 21, 2010)

Oh, really good points, Neven. Thanks! I will pass this info on to my son. He is old enough to contact manufacturers and find info himself. It's good to point him in the right direction, though, as he has not kept his own aquarium.



neven said:


> NP, phillips i think is making the push for the new lighting. They normally will have data available for their lighting if its not on the package. Just remember to have both bulbs facing downwards to make the results more accurate. Twister CFLs have greater restrike sideways compared to vertical, what this means in simple speak, Less light output when sideways. if you are simple desk lamps, or clamp ons from walmart, you should use double sided tape and strips of tinfoil to direct the light more into the tank, since LEDs are very directional.


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## Fansons (May 20, 2010)

Brighter does not equal to better growth rate. Spectrum is the key.


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## Morainy (Apr 21, 2010)

Right... spectrum! Maybe he needs 4 tanks, with different lumens and spectrums. Hmm. Thanks, Fansons.


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## neven (May 15, 2010)

i think 2 will do, he needs to think about a future project! he can use this one for a foundation to the next year.

Reason i say 2, because warm white and cool white/daylights for home use are often pretty equal in plant growth


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## Morainy (Apr 21, 2010)

Thanks, Neven.

This isn't a real science fair project. His science fair projects are usually quite complex and take months to complete. This is just a class assignment. The fluorescent light is the control, essentially.


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## Morainy (Apr 21, 2010)

Update: I have 2 Fluval Specs now. But am still clueless.

Each of the Specs has 31 LEDs. We can put them onto one tank if we have to. Now we want to find a fluorescent light that is somewhat equivalent. (For my son's science class experiment... it's not a full-fledged science project, just an assignment.)

I have not been able to find information about how many lumens or kelvins that Spec LEDs are on the Fluval website -- or anywhere -- and Fluval has not responded with this information. I thought that it might be easy to figure out just by counting up the # of LEDs but I've discovered that the diodes are not the same. The Eheim Aquastyle's light with 81 diodes produces 2000 lumens at 6000 k, or about 24.5 lumens per diode. (If that even makes sense) The Marineland LED fixture has about 10 diodes, 8 for daylight and 2 for night, producing 600 lumens, or 60 lumens per diode. A Hydra Aquatics fixture has 12 white LEDs and 8 blue for 332 lumens (various kelvins) or 16 lumens per diode (if the blue are counted).

I'm utterly confused! I'm going to guess that the Fluval Spec is roughly equivalent to a 7 watt fluorescent, just because 7 watts is what's put on nano tanks quite often. But of course, that's a wild guess. Maybe it would take 2 Spec lights to equal a 7 watt light.

The Spec tank is only 2 gallons (less if you subtract the filter) and not very deep.

Can anyone point me to some good information about the differences in LEDs so that my son can at least make an educated guess about what kind of light will match the LEDs? He's much more math-oriented and science-oriented than I am, so if I can put some good information sources into his hands, he will be able to take it from there.


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## monocus (Sep 27, 2010)

would a par meter help?the led tube lights i have are brighter than normal tube lights.also a cool white or blue will have a higher k than a warm white.i can lend you my par meter if it will help you out


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## Algae Beater (Apr 21, 2010)

generally a 9 watt led bulb and a 13 watt CF bulb are about the same in luminous flow give or take as most CFL are rated around 80 lumens per watt and LEDs or the 2 -3 watt variety are around 130 lumens / watt depending on manufacturer

another factor is a reflector for the CFL and their light is dispersed in all directions as opposed to the unidirectional LEDs


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## AquaSox (Jun 9, 2010)

monocus said:


> would a par meter help?the led tube lights i have are brighter than normal tube lights.also a cool white or blue will have a higher k than a warm white.i can lend you my par meter if it will help you out


I fully agree with this. I think you should measure PAR. Lumens are not a good indicator of potential for plant growth:

Lumens vs PAR - Grow Test in LED Grow Light Technology

But I guess you need the two lights to have the same lumen output for the sake of the experiment? Perhaps you could measure PAR for the fixtures after to explain the growth differences (if any).

Here are some lumen comparisons of bulb and brand types:
http://www.petsandponds.com/en/aquarium-supplies/c5813/index.html


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## Morainy (Apr 21, 2010)

Thank you, everyone! Wow, there is so much information here. For example, I've read the word (or acronym) PAR before but never bothered to find out its meaning. Monocus, thank you for offering to lend us your PAR meter. We may have to take you up on that, I'll wait to see what my son finds out. We could just take the lights to your house to measure, probably, rather than borrowing the meter. They're small.

AlgaeBeater and AquaSox, thank you for the info. I'll show your posts to my son when he gets home from school. He's hoping to set the tanks up this weekend; there's still time for him to figure out the lighting before planting them.

It's interesting to note that my question totally stumped Hagen/Fluval. It took them several days just to let me know that they've forwarded my question to their technical department to find the answer.

I did find that the similar Dymax IQ3 Robot light (available with the Dymax IQ3 nano tank or separately online) has 28 5mm LEDs @ 18.5mA/ea I don't know whether the Specs are the same... The Dymax's LEDs are over-amped or something, and dim in 6 months.


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## Morainy (Apr 21, 2010)

Okay... after reading the links, I have another question. What's the difference between a PAR meter and a LUX meter?


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## monocus (Sep 27, 2010)

about $300---lux meter cannot see the red or blue spectrum that well


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## Morainy (Apr 21, 2010)

Okay, that's a pretty big difference!~



monocus said:


> about $300---lux meter cannot see the red or blue spectrum that well


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## neven (May 15, 2010)

i would still recommend buying the lamps based on lumen output (ie bulb equivalent).  The par meter is great to show a quantitative value as to why your son got the results with each of the lights, the values should only come into the project after the experiment is established. Ie, why is one plant growing slower.

lux meter measures light in relation to the human eye
par meter measures light in relation to photosynthesis (plant growth)

http://www.bcaquaria.com/forum/equipment-talk-section-14/par-real-way-measure-light-4471/


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## Morainy (Apr 21, 2010)

Thank you, Neven. That seems like a good approach: start with the info he has, then look for more sophisticated explanations. He may have to set up more than 2 tanks.

I'm still waiting for Fluval to let me know the lumen value = or any technical details == about their Spec lights. If we can't get those details, he may have to swap out for the Dymax 3 Robot LED (very similar) because they do publish their specifications. We'll see.


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