水草情迷

Any guy think about using bright white LED light or blue plus red LED lights to make a DIY lights for grass growing.

I had found some info. that LED can have a 8000K colour temperature.

If it works, then there will not have any temperature problem arise from HQI lamp.

Please correct me if I am wrong, as far as I know, LED only emits light with a particular wavelength. If I am right, it is not very useful for plants which usually require lights with different wavelengths for efficient photosynthesis.

我唔知而家的LED 色

well. i already make a "night light" refer from this web site long time ago.
http://www.csd.net/~cgadd/aqua/art_nightlight.htm

I try to use the super light LED as light source(about $1x for one ). Per the web page, two red one and two blue one as a set. It can provide just like "spot light" when shot on the wall. But it is very dim when shot to the water.

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LED係出唔到k數
LED都冇k數尼回事
LED係用msn(唔記得係未咁串)計的

PS:我媽的工廠是生產LED的,如果有關LED的問題可以問下我~~

>LED係出唔到k數
>LED都冇k數尼回事

I don't understand, since kelvin is just a unit to measure colour tempeature of visible light, so any visible light can be measured, so Kelvin isn't something to be emitted, but rather a measurement of light. Maybe because its very easy to tune LED to an exact colour tempeature since LED can emit just one wavelength instead of a spectral of light, so the manufacturer don't care about colour tempeature spec.

To the original topic, since LED emit one wavelength rather than a spectral of light, this reason alone make it very unsuitable for growing plants.

I attach the link that i found that a K-value is assinged to the LED.

http://www.theledlight.com/technical3.html

I know that the ordinary LED is dim but the new bright one is now using for making touch. It shall be quite bright in that LED. I agree with that the LED may not be replaced the HQI now.

But it seems that replacing the HQI with LED is the perfect condition for us, where we live in hot environment. No cooling any more and more energy efficient. That is my view.

I hope some electronic guy can give me some idea that how many LEDs can replace a HQI.

Dear Chicken Wings, Colour temp. K is not the determinant of plant growth. You may also read the article of 'K'
http://www2.aqugrass.com/phpBB2/viewtopic.php?t=1658

LED can only provide monotonous light (single wavelength), but plant growth requires sprectrum of wavelengths in the regions of (430nm, 490nm and 680nm) Even you may find diodes which emit light of exactly the same required wavelength, it is still not good enough as it cannot provide spectrum of wavelength.

I suspect the best application of LED in fish tank is to function as 'night light' as mentioned by super unless, it can emit spectrum of wavelength.

Thanks Alex, you just give me a lesson. Thank a lot indeed.


As you mentioned, plant growth requires sprectrum of wavelengths in the regions of (430nm, 490nm and 680nm). I suppose high intensity of these wavelengths from LEDs will also help the growth of plant.

The point is that we are finding the light bulb/tube/HQI for the best growth of the plant. If LED can provide these wavelength, we can have much saving and solving lot of problem from HQI.

But we still shall solve out our eyes that LED may not provide a good mix of colour for us.

IC