Hydro Culture HPS Lamps

Re: Hydro Culture HPS Lamps

The problem with plant-bulbs is that nothing is added, just removed. To get more blue and red they filter out yellow-green. Energy loss. Nothing gained but uglier light.

You can calculate how much of the energy you put into the bulb is converted to ordinary human light, lumens. This gives you an efficiency how well the bulb produces photons in the human visible range. Together with the bulbs spectral distribution and a photosynhtesis action spectrum you can then calculate how many photons from the bulb that do good to plants. You have then calculated the Photosynthetic Usable Radiation efficiency. PUR-efficiency.

Sylvania GroLux has a PUR-efficiency of around 0.5 microE/Joule, compared to for example Philips Aquarelle (TLD89) with a value around 0.8 microE/Joule. I have calculated values for a couple of bulbs:
http://www.defblog.se/permalink/1402.html

Another take on this is that some bulbs only loses about 10% of its initial output intensity, GroLux/plant-bulbs are not included. But tri-phosphors like Triton, Aquastar, Aquarelle are.

All this is of no special importance when it comes to getting a nice planted tank especially not if you can afford the extra electricity and bulb-cost. With EI and good CO2-levels you will not find the light of any significance at all because you will manage to grow everything rather fast with surprisingly low light intensities.

But if you want to grow a plant faster than anyone else in some sort of growth-rate-competetion, PUR-efficiency would come into play. If you have an action spectrum for one specific plant I can tell you which bulb will grow that plant faster than any other bulb.

Re: Hydro Culture HPS Lamps

defdac, what is your opinion of the vita-light?i have one,and one factory fixture issued bulb over 20 gal long,for over 2 years and seems like crypts really grow good under this light,with no co2. regards,cornhusker

Re: Hydro Culture HPS Lamps

I would need the spectral distribution and lumens-output to calculate the PUR-efficiency for it. Will gladely add it to my list if you find it!

Re: Hydro Culture HPS Lamps

bennyss said:

There is specific Hydro Culture HPS lamp specific for plant grow.
For example Sylvania Grolux Philips plantStar.

Click to expand...

It had better PUR-efficiency than I thought:
http://www.defblog.se/permalink/1402.html

If you can live with it's extreme yellowness it would grow plants just fine 8)

Found the spectrum here:
http://www.hydromall.com/infocart_mfgs/plantastar.html
..and used the mean lumens value of 50000 from Sylvanias site.

Re: Hydro Culture HPS Lamps

Something went wrong when they did their datasheets because all three lamps have the exact same spectral distribution, two bulbs with different color temperatures cannot have the same spectral distribution.

The PUR-efficiencies calculated with the same spectrum but different lumens/wattages is 0.62 on the last two 150 watt bulbs, and 0.57 on the first 265 watt bulb.