Diffused light

[Ray]

Another interesting tidbit in the paper referenced by Terry that caught my attention - green light isn't useless! It penetrates deeper into the leaf than blue light. Another reason not to use the hideous red-blue LEDs.

Yes, the plant uses the entire photosynthetic spectrum, but the areas around red and blue are absorbed the most efficiently. If you don't care about appearance while growing, are trying to maximize the light generation per watt used - maybe so the police can't use your electric bill to pinpoint you - it's still a good way to go.

However, I agree with you about the hideous appearance. Since the human eye is most sensitive to the green part of the spectrum, it seems to me that adding enough to please the eye and feed the right amount of photons to the plant ought not be THAT inefficient.



Ray Barkalow
firstrays.com

 

[DavidCampen]

Naoki, David,
I do all the wiring myself, and come across quite a few issues with respect to ground currents(wonder if thats the word?). Our electrical system is more or less foolproof, cuts the main supply when there is an imbalance between the leads of more than 25mA. Prevents me from getting fried, but is a nuisance what concernes functionality. But then again, safety first!

Ground Fault Circuit Interrupter here in the US as Naoki mentioned. The transformers/power supplies for LEDs as well as fluorescent lighting have given me problems with tripping GFCI. I have removed my lighting from GFCI. Is it mandated that all your circuits have GFCI?

 

[DavidCampen]

Since the human eye is most sensitive to the green part of the spectrum, it seems to me that adding enough to please the eye and feed the right amount of photons to the plant ought not be THAT inefficient.

Ray Barkalow
firstrays.com

Assuming that a 550 nm diode and a 680 nm diode are equally efficient at converting electrical energy into photons then you get 25% more red photons per watt than you do of green photons.

 

[ALToronto]

Ground Fault Circuit Interrupter here in the US as Naoki mentioned. The transformers/power supplies for LEDs as well as fluorescent lighting have given me problems with tripping GFCI. I have removed my lighting from GFCI. Is it mandated that all your circuits have GFCI?

Sometimes even a new gfci is flaky - have you tried replacing the outlet/breaker? Also, the life expectancy of a gfci in a damp environment is about one year. After that it becomes more and more difficult to keep it closed. Are you having tripping problems with new or older gfci's?

 

[ALToronto]

Assuming that a 550 nm diode and a 680 nm diode are equally efficient at converting electrical energy into photons then you get 25% more red photons per watt than you do of green photons.

How is wavelength related to wattage?

 

[Bjorn]

Ground Fault Circuit Interrupter here in the US as Naoki mentioned. The transformers/power supplies for LEDs as well as fluorescent lighting have given me problems with tripping GFCI. I have removed my lighting from GFCI. Is it mandated that all your circuits have GFCI?

Thanks, they are mandatory here and are a nuisance. Nowadays every circuit has its own, but in my house there is a central one so when it breaks, everything gets dark. May be problematic if you are not home, but at least you notice it and can fix it immediately. Greenhouses are very demanding when it comes to finding the ground fault. I remeber one incident; seemingly for no reason the power went out, and I looked and I looked and everything seemed ok. And then zap, no light. Eventually I found the problem. A slime track after a slug inside one of the electrical heaters. Only when high humidity and thermostat set in there was an fault. It's that kind of problems you have to look for.
Yes naoki, I have electrical heating. But most of it is taken care of by the lights. The house has triple layer, double layer polycarbonate and no vents so lighting is sufficient to get temperayure up. During summer, cooling is mostly done bu duct fans and air-condition. Might sound expensive, but is actually much cheaper than having sufficient vents that leaks during winter.

 

[Ozpaph]

We have GFI( ground fault interupter) in Oz that you can plug into the power outlet to protect just that device. It saves the whole house going 'off' with each 'fault'. They cost about $30 here. I use then on my GH fans which can trip if they get too wet.

 

[Ray]

How is wavelength related to wattage?

Alla, if I'm not mistaken, it's simply a matter of how efficiently the particular materials used convert electricity to light. Specific materials emit specific wavelengths, and some are just better at the conversion.

 

[DavidCampen]

How is wavelength related to wattage?

The energy of a photon is inversely proportional to its wavelength. So a 550 nm photon carries (680/550 =) 1.24 times the energy of a 680 nm photon.

 

[DavidCampen]

Sometimes even a new gfci is flaky - have you tried replacing the outlet/breaker? Also, the life expectancy of a gfci in a damp environment is about one year. After that it becomes more and more difficult to keep it closed. Are you having tripping problems with new or older gfci's?

These were newly installed GFCI outlets. I have experienced this with multiple different lights on different GFCIs. On searching the internet I found aquarium hobbyists also commenting about this and the only solution proffered was to not use GFCI.