Backyard Aquaponics
A place to discuss aquaponics

gee, I am SO glad that we don't have to worry about artificial lighting. This discussion has gone "whoosh" straight over my head

I find it easier to understand if I squint Jaymie.

Makes you wonder why someone hasn't developed purple LED's.

There are purple LEDs! LED coloring has to do with what ions are used to dope the P-N junctions. Different ions have different electron excitability levels. When they relax, they give off energy as photons... ta da!! light!

But the purple is really the indigo/violet end of the high energy visible spectrum. Not the purple made out of red+blue, which is what the plants need.

And yes, I'm a geek and have a degree in this stuff

Go the geek's, there's a few of them on the forum

Never taken much interest in LED's for grow applications in the past cause they were expensive for the output. Good on heat and power consumption and life expectancy. (Bummer about the purple though)

Funny you should say that. I just found them. They are pure 470nm and 630nm so purple! You find them here just scroll down a little. They are 16.2 ¢ each!

There is a $100 minimum order. I was going to ask if anyone wanted to pitch in with me to order some, but the problem is wasted power.. Its a 1:1 red:blue ratio which means more blue light than a plant will use. 4:1 is needed.. Hmmm What do you think? Its pretty..

The only concern is that they are made in china. They use inferior dies and generally make a crappy product. IE. Their LEDS say life time up to 100,000 hours. USA leds say minimum life 100,000 hours...

What do you think?

China would be out, in my mind. Nothing personnel but industry is taking advantage of less then good enviornmental practices there. Time to make a stand for me. That will probally last less then a week as I don't know of much made in my country any more but I'll try as I can.
Sorry for the rant.

Good digging! Well, if a HID light uses 50 watts for 1 square foot that would be 5 watts LED light.. But When compared to the sun.. .4 W a meter. Im with you seems a bit dim.. I would be really simple to use 1 of those duel wavelength LEDs to grow a single plant and see what happens. A bean sprout would show us pretty quickly at that 1:1 ratio. If using normal single color LEDs at a 1:4 ratio you would draw .5 amps, but using the same number of purple LEDs you would draw .8 amps. So using normal LEDS vs purple LEDS would save 37.5% of the energy.

This is an experiment that I must try! IF a plant will photosynthisize the same using 30% light the same that a plant that stops photosynthisizing during the day because of pohotosaturation then thats a HUGE discovery. Combine that with the LEDs ability to produce only the wavelengths you need and little energy wasted as heat and you could afford to grow a greenhouse full of stuff year around!

This would be a great way to test out that time lapse camera I have! What is the fasted growing small plant you can think of?

It seems like making your own LED lamp is not terribly economical compared to getting one off eBay. There are a bunch there, and the prices seem about the same as making your own.

I think you are right. Ebay sells them for what it cost to buy the LEDs, but those have to be china leds..

However you can get 1 watt LEDS from digikey for .14 cents each.

That's entirely possible.

Look at the watt rating of those ebay lights. They are not the super bright LEDS they are the normal LEDs. The 900 LED panel pulls only 13.8 watts and its 12 inches square! Thats more than twice the light you would have to have.

I also noted that a few sellers said to use fluorescent grow lights also?

$130 sounds cheap for 900 leds, but just 5, 1 watt LEDs @ 2.16 each would only cost $10 and that would be all the light you need in a foot.

Well, you're assuming my calculations are correct

I've seen the same thing about the fluoros though. The argument is that they will provide the rest of the spectrum that the plants need minimally.

I forgot I have an old fashioned electronics shop up the road. I can probably cobble something together today.

Well, my local shop had some superbright blues, and I got 10 of them, but they are expensive as shit. $2.26 a piece. So I may be returning those.