Thoughts on lights for my wardian case please..

I have a 4 tube 4ft high output T5 set up and its rated at 20,000 lumen, that is significantly more than the ratings I saw for the few 150 watt metal halides I looked up online so I imagine the T5s would work well for you. They do put out a little heat but probably nowhere near as much as those metal halides. Is that some kind of cooler in the bottom left corner of the picture? If so, I would love to hear more about that.

 

No, the T5 bulbs are 4 ft long.

 

Brett, it looks like a very nice cabinet. Are you cooling it with the water cooler (the thing on the left side)?

I think 4x 54W T5 seems to be a bit weak for the height, but yours are similar size as Ron Hanko's
http://orchidsinbloom-ron.blogspot.ca/2013/06/rebuilt-orchidarium.html
and I think he is using 6x. I can take a PPFD (and/or fc) measurement of T5HO later if you are interested.

Is the fixture stay outside of the cabinet? If not, T5HO becomes inefficient at a lower temp. (LED become more efficient at the lower temp).

If you go with DIY LED, you can attach different lens/reflectors to have some light for the bottom (narrow beam angle), and other light for the higher levels (wide beam angle). For these individual LEDs are probable better (easier to fine tune the top vs bottom ratio, and spread). COB LEDs are easier (& chapter) to DIY, but the selection for the reflector may be a bit more limited. If I were doing it, I would put 2x Cree CXA3070 on the top (50W or so for each), and put 2 of those in the front door (for the lower level). Because of the inverse square law, getting uniform light is pretty tough in tall cabinets

 

Before I build greenhouse, all my light cabinets had HID metal halides above glass roof of the cabinets. That helps to decrease temperature in cabinet. Additionally: fans & plug-in thermostat worked as a supply and exhaust air system to keep temperature at required level. Thermostat was from pet store (think - terrarium) and has day/night temperature differential setting. That unit was my best investment! Still using it in greenhouse.

 

Here is some measurement of T5HO.

T5HO 54W x 4 Hydrofarm FLT44, room temp 66F, measurement at the middle (brightest point).
3x AgroBrite 6400K 54W (about 1-2 years old)
1x cheap 4000K 54W (a couple month old)

@ 1 foot
PPFD: 185 micromoles/m^2/s
Gossen Luna Pro: 730 foot-candles
LX1330B: 1410 foot-candles

@ 4 foot, it is about 1/10 of these values. You would expect the value to be 1/16 from the inverse square law, but since the light source is not a point source, it doesn't quite follow the inverse square law.

If you use plant bulb (purplish one), you can get about 40 % more PPFD.

The bulbs are pretty old, so you'll probably get 30-45% more output with the brand new bulbs.

Gossen Luna Pro is recently calibrated, professional photography meter. But the spectral response is not quite following the standard. LX1330B is a cheap light meter, but it is fairly new, and the spectral response in the manual seems to be pretty good (I don't know how true the curve is, though).

 

Thank Naoki, I have the same hydrofarm light set up so it"s interesting to get an idea of the measurement mine puts out. Which of the two light meters would you put more stock, or to put it another way, what do you think the actual light levels are? I am suprised both readings are fairly low, even if they are so different.

Brett, my T5 set up is not in a terrarium (my terrarium is a tiny exo terra light by a 13 W CFL) but in a open growing area in my kitchen. I have the lights suspended maybe 2 and 1/2 feet(76 cm) from the counter the plants set on so most of the plants are probably 30 to 60 cm from the light depending on the height of the plant and pot and if it is on a riser. I have only been growing under lights for a few weeks but I am definitely seeing new growth and some slight redding of leaves so hopefully my plants will like it.

I am suprised the readings Naoki got are so low considering that I am getting red coloration in my leaves meaning they are getting pretty high light. I guess the cumulative effect of a constant lower level of light exposure during the day makes up for the lack of intensity in the mid day.

EDIT; forgot a word

 

Dave, I don't know which fc meter is more correct. But the cheaper LX1330B is more likely to be closer to what many hobbyists use.

But PPFD is a much better measurement than fc. Many people may not know how to interpret PPFD. You can think full sun at noon is 2000 micro moles/m^2/s (and 10000fc). So basically, if you multiply PPFD by 5, then you get the fc equivalent to sun (185 * 5 = 925fc). However, you should note a big difference between continuous vs natural light. When books recommend fc values, they are the peak intensity of natural light. With continuous light, you can use much lower amount to get the same cumulative amount of light. According to some simple calculation (and using their parabola model), with 12hour day, you can give 2/3 of the peak intensity. In other words, if you use 1000fc continuous light for 12h/day, then it is similar to natural light with 1500fc. You can't compare the fc of fluorescent light with sun, though, because fluorescent light has less PPFD per a given foot-candle than sun.

But in reality, with artificial light, orchids seem to do well with much lower intensity than the converted values from the recommended light intensity for orchids.

I'll post more detailed data (I posted in another forum, and I meant to post here, too, but I forgot). But the low output is likely due to the decay in the output. The other thread will talk about this.

 

Are you talking about the 90W blue Kessil A350 instead of H series?
http://www.kessil.com/aquarium/A350.php
It would be interesting how orchids respond to blue only source. In theory, you could get more PAR for a given watt, but photomorphogenesis side may or may not cause a problem (small leaves due to cryptochrome mediated response in other plants).

I have not figured out why Kessil stuff is so expensive (well I haven't found their PAR numbers in their spec.) Their explanation of advantage of high-density LED seems to be backward, too. With a point light source, upper leaves create big shadow, and lower leaves don't receive light, so it is more advantageous to have a panel of LEDs than a point source (one advantage of fluorescent light). This is one of my complaints about COB LED.

 

That's a misconception I have read over and over - "LED light doesn't penetrate as deeply as other sources".

A photon is a photon is a photon, no matter the source. It's the photon flux that matters. I think where folks' thinking gets misapplied (not yours, "s*", as you actually measured) is the use of "equivalent" wattages, or in the case of white LEDs, the predominance of green in the spectrum, which the eye perceives as being REALLY bright.

A 13 watt LED ("60-watt equivalent") is going to put out 13/60 of the light of 60 watts of T5 (assuming both at about 90 lumens/watt), so will have 21.67% of the "penetrating power".

 

Brett, what was the measurement from Kessil A360?

You are right about the sales person; from the data I have seen, it is unlikely 90W white LED has the same PAR efficiency as 250W MH.

I understand what you are looking for, now. It is true that many pre-made LED fixtures have wider beam patterns. But I'm sure there are some with narrow beam; Build My LED can have narrow beam pattern (30 degree). An independent test confirmed that one of BML's model is highly efficient, but I don't think it is available in Australia.

With LED, the spread of light can be controlled by optics (either lens or reflectors). Since you are pretty handy, DIY LED sounds like the best way to go. The cost will be 1/2 to 1/3 of the Kessil (even with high quality components), and in this way, you can control the beam pattern to suit your need. For example, DavidCampen posted his DIY LED with narrow beam angle in another forum (here and here). And I posted about DIY COB LED with CXA3070 (the measurement there was with a Gossen light meter, which gives reading much lower than the other cheaper meter, and if you multiply the values by 2, it is similar to a cheaper meter). There are some narrow angle reflector for COB, too. For example, ledil makes several different reflectors and lens for CXA3070.

 

Brett - the drivers in many LED lights can handle a wide range of input voltages. One BML lamp I was looking at states 100-277V, so you should be OK.

 

FWIW, I've ordered LED light fixtures from BML twice now, and their products are first rate. Beautiful build quality, and terrific customer service. -Stephen