4200k vs 5200k mh lamps

[Joachim Danz]

Hi,

recently I did change my MH-lamps from 4200k to 5200k. I took two photos with my digital camera which show the different colouration. Digital cameras are not best to show colour differences I know, but the result did match my visual impression very well.

4200k:

5200k:

I don't expect any major effect on my plants, but it does look more "natural" right now.

Joachim

 

[Khai]

I would think you might see a slight shortening of nodal legnths, the 5200k is clearly a whiter light.

 

[Tony Paroubek]

Alot will depend on the spectral peaks and where they fall in relation to usable light to the plants. What we see and what the plants are able to use for photosynthesis are not the same. Any way of getting spectral graphs for the two different bulbs?
Tony

 

[swords]

Joachim,
What wattage of MH are you using? I have a 250w Metal halide that I just set up tonight on my lowland chamber and it's supposed to be 6500K but it is very dim compared to even my 110 watt 6500K power compacts. I'm very dissapointed with this MH.

 

[joseph]

swords, sounds like you have a problem. That bulb should be much brighter. Where is your reflector directing the light? Where did you get the ballast from? Where did you get the bulb from? (I'm hoping you don't say e-bay).

Just saying you may want to look over your setup.


joe

 

[Joachim Danz]

Hi Khai,

I'll watch for the shorter internodes. I don't expect that much difference, as I am growing these plants with lots of natural light and do use the artificial light mostly to increase daylength during winter.

The spectral distribution is given on the last page of the datasheet of the new lamp ( http://www.blv-licht.de/images/BLVMedia0018305.PDF ) ond the 4200k lamp should match the blue curve plot labeled MHN on this page: http://www.hereinspaziert.com/Sehlicht/Bild11.htm
The green curve in this plot should be the typical spectral efficiency of plants.

What already did happen, is that I badly burned my N. inermis and the N. faizaliana and the N. glabrata have changed to totally red leafes right now.

Josh, I am using two 75W MH-Lamps for my terrarium sized 120cm x 60cm. Two lamps are preferable over a single one, because I don't get that sharp shades under the plants like they would appear with a single lamp.

Joachim

 

[Khai]

Yes i can see how that wouldnt make much difference.
Swords sounds to me like theres something wrong with your MH, do you have another bulb you can test?