# Full Spectrum vs......



## arc (Mar 11, 2010)

I just found a source for some "Full Spectrum" CFL with a CRI of 92 and colour temperature of 5000k.

Does anyone know what the difference between this and the normal "daylight" bulbs I get at Home depot(6500k)? The cost of the "Full Spectrum" is more than double of the daylight ones.

Since plants seem to grow well in daylight bulbs I imagine its a marketing thing but just wanted to know if anyone used these "Full Spectrum" bulbs and their experiences.

Thanks in advance


----------



## 5318008 (Dec 11, 2010)

It depends on whether the daylight bulbs are full spectrum as well as the terms 'full spectrum' and 'daylight' refer to different properties of the light bulb. CRI describes how accurate the light colours/spectrum is (on a scale of 0-100, 100 being the best rendition) hence how 'full' the spectrum is whereas 'daylight' refers to what spectrum the light bulb operates in. Whether each light bulb is best for plants would depend on the actual light emitted by the bulbs (can vary significantly depending on brand, quality, spectrum, type, etc) which would be measured by a par meter.


----------



## BillD (Jun 5, 2006)

The above is true. Full spectrum is a generic term used to describe lights that are close to giving natural light and honest colour rendition. The Philips 5000K Bright White CFLs are the same price as the 6500K Daylight. They will grow plants as well as the 6500K, perhaps better. I don't know what the CRI is for those CFLs, but they can be had for a good price now as the rebate coupons are out for them and on the shlves at HD.
For anyone using the 23 Watt CFLs, a 4 pack is only a dollar more than a 2 pack and has a $3 rebate, so that the cost is around $7.50 for 4. They are available in both 5000K and 6500K.
The colour temperature of sunlight at noon at the equator is around 5500K, and the CRI is 100. The so called daylight (6500K) more closely resembles the light of morning or late afternoon.


----------



## arc (Mar 11, 2010)

Thanks for the info and the heads up about the lights discounts. I found out from a wholesaler that the CRI for most CFL is around 80-85 and its gets lower as the colour temperature goes up. So I guess I'm paying for the extra CRI but with the price breaks I can't see that extra 5-10 CRI makes that much differences.


----------



## BillD (Jun 5, 2006)

CRI is variable by individual lights. For example Philips T12 Natural Sunshine 5000K tubes have a CRI of around 92 and the T12 Daylight 6500K is around 84. In T8 the 6500K tube has a higher CRI than the 5000K tube, although I don't remember the numbers. In fact there are some Cool White tubes with very high CRI numbers. Manufacturers can improve the CRI without changing the colour temp, to a degree.


----------

