# About Lighting and Pearling



## Vivian Andrew (7 Nov 2014)

Hi,

I have 4 X 39W T5 HO light where I'm using only 2 bulbs, whenever i use 39W 12000k bulbs which comes with the fixture the plant doesn't pearl and when i change my bulbs into 39w 6500k it start pearling in 30-45 minutes, and when i switch to 12000k it will stop what is the reason behind this?


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## prdad (7 Nov 2014)

*pulls up a chair and orders some popcorn*


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## ceg4048 (7 Nov 2014)

Vivian Andrew said:


> I have 4 X 39W T5 HO light where I'm using only 2 bulbs, whenever i use 39W 12000k bulbs which comes with the fixture the plant doesn't pearl and when i change my bulbs into 39w 6500k it start pearling in 30-45 minutes, and when i switch to 12000k it will stop what is the reason behind this?


Spectral content determines which pigments and distribution are developed and are present in the leaf. Depending on the pigment distribution, it can easily occur that the opposite happens wherein higher photosynthetic rates occur with the 12000K bulb. 

So if you use only those 12000K bulbs for some time the pigment distribution in the leaf will change to match that particular spectral distribution.

PAR output of the individual bulbs also are an important factor. Bulbs having higher PAR output will drive higher photosynthetic rates.

Cheers,


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## Jose (7 Nov 2014)

Or simply said: they have different PUR (Photosynthetically Usable Radiation) range. Right?


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## Vivian Andrew (8 Nov 2014)

Thanks for the clarification clive, one more doubt 



ceg4048 said:


> it can easily occur that the opposite happens wherein higher photosynthetic rates occur with the 12000K bulb



so if photosynthesis rate occur high in 12000k bulbs that means it will consume more co2 ?


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## ceg4048 (13 Nov 2014)

Anytime the usage rate of light is high the CO2 consumption will also be driven high. The purpose of the light gathering phase of photosynthesis is to derive enough energy to strip Carbon from CO2 in order to make a Carbon based product we know as sugar, so this is a fundamental relationship.

Cheers,


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