Backyard Aquaponics
A place to discuss aquaponics

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The subject of lights to grow the plants has been discussed under many topics. I thought it needed its own topic. Whether under plants or hardware was hard to decide. Moderators...do you want to move it? Fine with me.

I will start by providing information on FloureX fixtures that claim wide spectrum white light with high blue content. The front, side, and back panels are in my photos. These are cheap, readily available, and long lasting and energy efficient. Then again, what might be the down side?

Steve has had doubts about these...Steve can you give reasons or say what the right questions are? Steve likes MH (metal halide??) Let us discuss what lights can have a place in AP.

The FloureX are from 'Lights of America'. I will check their web site for more info.
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Thanks for starting the thread Doug.
I get confused with the numbers CFI? I'm currently playing around with some Compact Fluoresents (2700K) what ever that means. Only 9 watts each. Bad side they contain mecury.
Hoping to set a few up for my inside Guppie Salad Bar.
Anyone know how the CFI number converts to the K value?

lol isnt just Steve that has doubts.............MH lighting has always been the best for indoor growing, in particular the phillips SONT lamp....highly recommended in the indoor "funny tomatoe" plant industry....and coz it works for them who are we to argue lol, MOSTLY because of the content of the light emitted.....fluros just dont do it.....unless your using a grotube that emits the useable uV wavelengths.


I would seriously recommend those lookin at CF's to look at the growtube type in 18w (2ft tube). I have always had great success with those, and reckon that the CF's are only good for general lighting (as for growing plants I'd compare ti to pissin in the wind aka pointless lol)..........BUT I would be interested in seeing the figures/specs on the light output Doug....ANY useable UV in those fittings would probably be useless after 6 months anyway

MH are also more efficient than FL (by a factor of 2 from memory). The reason for this is quite simple - a fluorescent light works on the same principle as a MH, except that the resulting UVC light from the mercury discharge is then converted to visible light by the coating. This extra step is lossy. Metal halides instead emit visible light directly from the discharge. This is also their weakness - the colour depends strongly on the balance of the metal ions, and some metals are more reactive than others and become unavailable. This means that their colour drifts quickly and are thus unacceptable for use where colour perception is key.

Xenon discharge lights are better still as they produce something close to sunlight from a single gas, but they need to operate at high power densities which makes continuous operation difficult. They are also expensive (xenon is a very rare gas).

I wonder if xenon headlights would be worth considering? 9 in series might work from US mains supply (don't do this unless you know what you're doing).

(amusing anecdote:
When I was a kid I made a continuous xenon light using a cheap xenon flash tube inside a PET bottle filled with water. I powered the light by rectifying the 240V mains and using a flash capacitor as a filter. I used a hot water service piezo ignition thingy to trigger the light.

It all worked perfectly and I was treated to a thousand suns of light for 10 seconds. Then my eyes started burning and my skin prickled. I was getting a lifetime dose of UVC in seconds. I'll probably die of skin cancer now...

I did run the device again a few times from behind a thick piece of glass, but the glass tube melted (the water actually formed a layer of steam between the glass tube and the water) after a few minutes of operation and I gave up on it as a dumb idea.)

GotFish, the CFI is a new one to me too. From the box, it appears sunlight is CFI = 100 & these are about 75 and better than murcury vapor. The 2700K from the CF is a color temp as talked about in photography. The higher, the better at being like sunlight (wide spectrum light like plants respond to). The unit I show above has a value of 6500K, which should be white enough for plants. Notice they mention a large blue light component. Isn't that what is needed by fruiting and flowering plants?

BK, glass stops UV very well. Sun light through glass has most UV filtered out. That is why you do not get a tan working in a greenhouse or driving in a car with the windows closed. Plants do not need UV to do well. The full visible spectrum is fine. Notice that these Fluorex tubes are not standard CF. They have color temp of 6500K. Their web site claims 87% efficient (13% heat/ 87% light).

njh, I think you are quoting for CF and not these Fluorex bulbs. MH is not 2*87% efficient. The xenon UV burn you got would have been done easier with a carbon arc (like welding). I was lucky I did not permanently damage my eyes doing this when I was young. We did see spots for some minutes.

What is the color temp of MH? I know they work well. To me their parameters provide a standard to measure other possibilities by.

The Fluorex info can be found at www.lightsofamerica.com. The life of 10,000 hours would be fine if the 6500K, CFI of 75, and color spectrum stays acceptable that long. They are cheap at $50 - $75US per full unit (power supply, fixture, and bulb. The replacement bulb is only $10.00US.

I think the Fluorex bulbs need to be investigated as a seperate technology from CF. They sure have different specs.

I don't believe the claims of 87% efficiency:
http://en.wikipedia.org/wiki/Luminous_e ... s_efficacy
Now this is human vision efficiency, but PAR is much the same (though with a different curve). Even the most efficient light sources (things like quantum dot lasers) are rarely more than 50% efficient.
http://en.wikipedia.org/wiki/Photosynth ... _radiation

8.7% is more likely, which agrees with the claim of 70 lm/W (4550lm/65W)

The good news is that there is lots of room for improvement!



Actually, the colour temperature is the closest blackbody spectrum. The sun itself is roughly 6500k, but due to its amazing intensity we tend to see it as bluer than it really is (the sun is actually pink if you look at it through a neutral density filter!). The reason we use low temperature lights is because they are 'warmer' and more friendly to human skin. Plants actually need pink light, and one day CFL manufacturers will work out a cheap PAR spectrum light and we'll all use those

Thanks for the PAR link NJH, very helpful!

GF, CRI means color rendering index; the description is on the box in the second picture Doug posted. A lot of lighting measurements are relative to human perception - lumens is one for brightness, CRI is another. A high CRI menas that paint and fabric colors for example will look similar to what they do in natural light, like with a full spectrum. A bad CRI would be something like sodium lights where everything is yellow and some colors fade to gray or black. This is less useful for us.

The ideal would be a light that efficiently puts out the wavelengths to excite the chlorophyll molecules. Somewhere on the web I'm sure the useful bands are listed (like here: http://www.chm.bris.ac.uk/motm/chloroph ... hyll_h.htm ). I wonder if only those wavelengths are necessary and you'd be wasting energy if you generated ones outside the sweet spots.

For color temperature, this is an "average" color even though the light may be made from multiple distinct wavelengths. Some kinds of lights can't be well represented by color temperature (like fluorescents), but ones incandescent-like can be. I like the example of a sunrise on a clear morning - the light goes from orange on the horizon through pale yellow to pale blue to blue; the color temperature scale looks just like that.

(I had to learn some of this for work (computer rendering))

Exactly, and with the right phosphor choice we could considerably improve the absorbtion, as you say. I'm just waiting for a CFL manufacturer to sell something like this for a price comparable to ordinary CFLs. (Not that I grow much under lights any more)

I just started digesting this page. It looks promising.

http://www.thekrib.com/Lights/

and this section

http://www.thekrib.com/Lights/mh-vs-vho.html

said UV meant useable wavelengths

Nice links.

I've been thinking about the general assumption that guides this topic - artificial lighting. How necessary is artificial lighting in the cooler climates? Has anyone looked into using heliostats or even large white painted walls to increase the photon count to a suitable level for aquaponics?

What is clear is that even the best light sources are quite inefficient, and in the case of 'energy descent' would be totally impractical.

(On the other hand, if we are studying aquaponics for our trip to mars, these considerations are quite important. If you were travelling to Mars as the aquaponics engineer, which light technology would you take with you? Cost is clearly not an issue, but efficiency, weight and lifespan are.)

What about venus...

Doug,

With out looking at all the links yet...................

Was surprised to see HPS soo far down the list!

but notice how MH isn't on the table? LOL when ever you see one missing from a comparison list its becasue its BETTER than the product being flogged

Also to summarise (i think i'm right here) PAR is for plants Lumen is for people

you can have have a huge intensity light missing the blue and red spectrums that plants need and it would be next to useless (say a green) for growing plants.

IMHO MH is the go.

The reason i was so surprised with the HPS rating is not as scientific as what it was sociology...............HPS and MH are the two mainstays for people growing indoors (no, not me, i just like to read ).

MH are available from around 150W right through to 1000W, and any one that has stood under a 1KW MH can tell you its BRIGHT!

Also good to remember, wheather it be for Fluro's or MH lights, they have a life rating in hours. Yes, they will burn for probably atleast double thier life, but the light output for power output dropps dramatically, and in the case of MH the chance of rupture increases dramatically. So, unless you want 1000C glowing quarts scattered around the room, please don't use them much over their Hour life rating

lol im doin well....... son-t agro ( one of the most popular)= hps not mh......I still say fluro's are a waste of time.


doug, try something different and google some "lighting for home grown m" sites or similar and it might change your mind

Our days are pretty short and dark now, and even folks with good access to sunlight will extend the length of the day with artificial light. For many years, I raised seedlings for the dirt garden during the early spring. The first couple tries were in the sunroom with no artificial lights. (Sunroom walls are white, no heliostat.) The seedlings were all spindly and weak. (tomatoes, capsicums (peppers), and eggplants) When I started raising them under big banks of grow lights, they did wonderfully.

Of course, if you're working in your basement like DD is, all of your days are short and dark.