# Curious, Do you consider LUX when buying bulbs?



## GDominy (Jul 30, 2002)

I ususally try to get bulbs with a LUX rating of 90+

I was wondering if anyone else even considers this when buying??


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## Steve Hampton (Jul 22, 2002)

Do you mean CRI instead of Lux?


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## GDominy (Jul 30, 2002)

Oops. lol yes


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## GulfCoastAquarian (Jul 30, 2002)

I usually don't. The CRI rating is detrmined by the appearance of objects in air, not water. There are some "low CRI" bulbs that make fish look fantastic while some high CRI bulbs that wash colors out to no end. I usually just look for lumens output (your mistake might have been a Freudian slip! lux is more important to me than CRI, hehe)


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## inxs (Jul 30, 2002)

I have a hard enough time finding the color temp on most bulbs not sold through specialty sites/stores - can you explain CRI & Lux and is there a site that may list them for popular sizes of NO bulbs normally available at hardware stores etc?

Thanks


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## Steve Hampton (Jul 22, 2002)

> _Originally posted by inxs_
> I have a hard enough time finding the color temp on most bulbs not sold through specialty sites/stores - can you explain CRI & Lux and is there a site that may list them for popular sizes of NO bulbs normally available at hardware stores etc?
> 
> Thanks


What's important to note is that in order to compare the Lux of bulbs, the bulbs have to be installed in your tank and then measurements taken with a Luxmeter. Considering that most bulbs are in the $3.00 to $10.00 range it seems far more logical to me to simply purchase difference bulbs and try them in your tank as opposed to purchasing a $150.00 Luxmeter. Here's a very consice and accurate decription of Lux and CRI taken directly from George Booth's Website:

Lux

Lux is a measure of the actual intensity of the light falling on a specified area and is a much better way to describe lighting requirements. Lux is defined as lumens per square meter. Unfortunately, since lux depends on the how the light gets from the bulb to the area, the manufacturer can't specify it - it has to be measured by the aquarist. Hobbyist luxmeters are available for under $150 and are invaluable for the serious light cognoscente. Also note that since lux are defined in terms of lumens, they also suffer from a bias towards human eye response. 

CRI

This is the Color Rendering Index and describes how closely a light source renders colors compared to "standard" sunlight as observed by a "standard" human eye. A perfect source would score 100. Full spectrum bulbs rate in the 90s. CRI is usually specified for higher quality fluorescent bulbs but does not seem to be a valuable measure for bulbs used in planted tanks. Bulbs with a high CRI may not necessarily have the right spectrum for plants and may not be bright enough for good plant growth.

Here's the complete article on lighting from George Booth's site:

George Booth's Lighting Article

And here's a site that has some popular bulb's listed with Kelvin, Lumens, CRI, and Spectrum listed.

Hoa G. Nguyen's Website

HTH,
Steve H.


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