T8 vs T5 HO vs (maybe) LED?

[Tiny Tim]

FourOaks, I'm not so sure I'd trust a comparison chart or graph. LED's measure light spectrum using PAR. HID measures using Lumens.

Either way old school growers will always favor HID, new growers will swear by LED.

This is why I purchased a Mars II 400 watt LED, it claims at 190 watt actual draw it compares to a 250 watt HID. I also purchased HTG's 250 watt magnetic ballast HPS for comparison.

I can verify it does produce close enough to call it a tie. I have nothing to gain from making this statement. I also know when running my HID in the summer I need to add the cost of running a small 5000 BTU air conditioner continuously. I do not need to do that with the LED. You also need to understand watt to watt is not the best comparison. The LED's spectrum is more efficient than the HID. Also,when you actually compare watts required for indoor growing, consider the air conditioner and blowers running for air exchange. For your green house those might never be necessary. Good luck and Happy Gardening.
Tim

[FourOaks]

Tim...

So in a nutshell, what your saying is that a 1000 watt LED is NOT needed to replace a 1000 HID system, correct?


You would think some mfr. out there would make it easy. Like with a simple breakdown of what equals what.

[Tiny Tim]

bower, I'm seeing the same poor results with my new shop light LED. It's NOT the same as my full spectrum LED's. Maybe the plants just need more time to adjust, or I'm expecting to much from a 40 watt fixture.Like you mentioned, mine is also in a cooler room and it puts out very little heat.

[bower]

Originally Posted by Tiny Tim

bower, I'm seeing the same poor results with my new shop light LED. It's NOT the same as my full spectrum LED's. Maybe the plants just need more time to adjust, or I'm expecting to much from a 40 watt fixture.Like you mentioned, mine is also in a cooler room and it puts out very little heat.

Well this morning I decided to get to the bottom of it. Took pics, took off leaves checked undersides, didn't find an insect cause so I did a google for tomato leaf edema (the term "intumescence" is also applied to this physiological condition) and guess what. Light spectrum issues came up right away.

https://ag.umass.edu/greenhouse-flor...-intumescences

"..Recent research indicates that light quality, specifically ultraviolet-B (UVB) radiation is directly related to preventing or minimizing intumescence symptoms on ornamental sweet potato and tomato,.."

http://hortsci.ashspublications.org/...6/712.abstract
Far-red and Blue Light Synergistically Mitigate Intumescence Injury of Tomato Plants Grown Under Ultraviolet-deficit Light Environment
Yes, the text refers specifically to LEDs

Attached below, a graphic of research results from:
http://msue.anr.msu.edu/news/does_li...pment_of_edema

And pics of the edema on my tomato leaves. One interesting thing, they say susceptibility varies by cultivar and for me, there were more-less-and not affected plants in each group of F3, F4 etc so I could make this a point to select away from that susceptibility.
I'm satisfied that the LED shoplights are good enough for greens. I could probably make them usable for tomatoes by hanging the light in one of my window spaces, so they get natural light as well. Will have to look at my plant shuffle options and decide what to do...

[oakley]

I'm not having the issues some are having. Certainly not like some of the youTube
videos. Most are just not doing precise 'controls'. Not good enough for me any who.

I had a bit of burn under the full spectrum but those three plants are dwarf project
plants at about 2 ft tall now, not starts. (they also spent a few days in a sunny window)
NOT a controlled study.

Under my LED shop lights....top pic end of January, and last week some of the micros
potted up.

[oakley]

And micro greens I've been growing all winter. I grow much longer and more
into the baby green stage.

[FourOaks]

Oakley.. would you care to share the exact lights that you are using? If you already pointed this out, I missed it.

[Greatgardens]

Really interesting links!
GG

[mobiledynamics]

Bowers . Thanks for the link. I was concerned about mine as well - and while I was looking primarily on the surface view (topside) - leaves were borderline green purples. And when I looked on the backside, indeed they are straight up purple like your pics !

[bower]

Yeah I am just using a 4000 K LED shoplight and had one set of problems (fine for some greens, just not for tomatoes) and you can see this pic as well, with a lot of purple on the LED seedlings:
http://www.tomatoville.com/showpost....6&postcount=19

It sounds like you have the real deal for LED grow light and should be able to tweak it so they are getting all the spectrum they need... narrow band at 4000 and 6000 K doesn't seem good at all for the maters. And TinyTim tried out another one, said he had problems too.

[mobiledynamics]

I'll try to grab a pic. The leaves on mine look in coloration to the ones on the right on the ;linked pic. They do not look bright healthy green at all. However, while the leaf growth itself does not look good on the right side pic, mine are flourishing day by day.

[cwavec]

Just a quick comment here. I could add more and probably should but don't have
all the info in front of me or the time to find it right now.

I have several shelves (structure is a separate topic but I like what I have) each with
three shoplights strapped together. That is six T8 tubes above each and they are all
overdriven, so I get lots of light. They are on pulleys, so I can raise and lower at will.

This arrangement has worked well for me but I would NOT do it again. Here's why:

1) It is virtually impossible anymore to buy a decently constructed shoplight. This is so
sad because, after all, the shoplight is almost an icon of the American life. But they
are just not made anymore. I got mine around 2008, almost the last lots before the
manufacturing went to crap. What you would get now is so expensive you couldn't
afford more than one or two for this purpose and they will still be junk. The ballast
inside will be garbage and likely burn out in less than a month even if not overdriven.

2) Flourescents are going out of use anyway. I was surprised to find this out because
I have been dependent on them. I don't care between T8 or T5 - they will all be gone
in just a few years. Take a look at the product mix in any HD store and you should
conclude the same. I have great service out of what I've already built but definitely
would not build more.

LEDs are coming into play here. There is a lot of junk on the market and even more
that is just not suitable for plants. However, there has been some genuine attention
to making LED arrays specifically designed for plant growing. Have a look at the
following urls:

http://www.cree.com/led-components/m...ds-CXA3590.pdf

http://www.cree.com/led-components/a...s/horticulture

This is what I would use now on any new build or possibly a successor product
since they seem to be advancing so rapidly. Building this might be too much of
a challenge for some folks by the time you worry about the right power supply,
area coverage, etc. but there are a couple of companies providing everything
in a kit.

Sorry for the sparse info but I just don't have the time right now and, besides,
you can look at google and find lots of related material.

[Greatgardens]

My experiment with Daylight 6500K LED tubes has ended. For whatever reason, my plants just don't do as well as with Fluorescents. My small square fixture with the Red & Blue LED's did just fine. So I swapped out a garage 4ft. Fluorescent fixture for one with the LED tubes. Back for now to what has worked for a long time!

I also noticed that Amazon has just about stopped carrying 4ft. T8 fluorescent tubes. But I suspect that breakage during shipping played a role in that decision.

-GG

[cwavec]

No question the spectra are different and, yes, I have had good luck with
fluorescents as well.

But bear in mind a couple of points:

1) The 6500K designation is almost meaningless unless you look at the overall
power spectrum. When you do that, you will find that the spectra (at least
considering only fluorescents) are almost the same no matter the Kelvin
rating. There is nothing inside that tube at a temperature that high or even
at 2200K. The Kelvin temperature rating on all these products (LEDs too)
is basically a mathematical/ perceptual trick to make you think the emitted
light is more "white", "red", "blue", "warm", "cool", "daylight" or whatever, etc.

2) You need to look at the actual spectrum power distribution and compare
that with the efficiency spectrum for photosynthesis. This information is
documented and publicly available. If not doing that, you might as well
stick with almost any fluorescent tube, whatever the Kelvin temperature.
Plants don't care anything about the hype associated with any of these
designations.

3) In using LEDs, the Daylight 6500K designation is probably even more
useless and using a fixture that someone dreamed up using red and blue
LEDs is just a handwave in the wind. If you have one and it works for you,
stick with it but understand that you don't understand why it works and
neither does anyone else.

4) The reference I made to LED lights is not to any of the aforementioned
items but specifically to a product developed by Cree explicitly for
horticultural use. They document their technology to an extent that if you
have the stomach for it, you can actually determine what is happening in
the relationship between lights and plants. That is the route I would take
if I were going to build anything new.

That said, please note that a substantial portion of my comment had to do
with poor quality manufacture (shoplights) and/or future lack of availability
(fluorescent tubes). You cannot buy a new shop/garage fluorescent fixture
anymore that is worth having. Everything I have seen in the last 7 or 8
years is either crap or too expensive. Fluorescent tubes will be gone in just
a few years. You will barely be able to get any and even then only at a
price associated only with rarity more than quality.

[Greatgardens]

"Fluorescent tubes will be gone..."

Yes I agree, but I think more than a few years. Those dinosaur T12's are still around and considering the life of fluorescents, it will be quite awhile before enough life cycles of the fixtures/bulbs have expired to warrant extinction. Unless, of course, the government puts it very heavy thumb on the scales (one way or another). Where LED's currently come up short is with higher wattage bulbs. They just haven't developed a product (yet) that gives a say 150 watt-equivalent bulb (that looks like a typical residential A19-A20 form) at any reasonable price. So, larger CFL's should be safe for awhile longer.

But the flip-side is that LED's should continue to improve. Hopefully, plant-specific tubes will appear in larger numbers at lower prices. My 6500K LED tubes do great for my wife's cactus -- just not for tomato seedlings. At 19 watts/tube, these tubes give lots of light! (And I have no idea what the actual spectrum of these tubes looks like.) I may also modify my seed starting shelf to provide more headroom. That might be helpful.

-GG