T8 vs T5 HO vs (maybe) LED?

[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

[bower]

Just a couple of days ago I potted up the peppers that have been sitting more or less contented under the 4000K LED in spite of their long wait. I expected them to be quite rootbound, however this was not the case. I've never seen such poor root development. Yes it's not impossible I missed the mark with my potting mix. But also possible they did not get the light spectrum they needed. In my judgement the light is at least partly to blame, and I will be looking for an LED that better approximates the natural spectrum.

[cwavec]

@Greatgardens
Well, if you still want some, better get them now! Of course they are around.
I still have T12 fixtures in my family room with magnetic ballasts no less. They
have been lighting without a flicker for twenty-some years and I expect them
to continue.

But you are not going to get them in the future. In fact, I believe I could not
get them now. Yes, I can go out and buy a few T12s. They will not be the same.

Newer fluorescents don't last the way they did. And we don't even drive
them the way we used to. The old starter cartridges had a reason for their
existence. Also remember the fixtures you can buy now are generally
garbage or too expensive. And the electronic ballasts don't last. Don't even
consider the ones you would get in Lowes or Home Depot. A working life of
5 minutes to half an hour is a long time for those. It's not just cheap
manufacture either. An electronic ballast has inherent problems that will
cause any of them to fail much sooner than a magnetic ballast. They can be
made with more reliable components but the basic weakness is still present.

No, those guys are goners and it's happening now.

Don't expect LEDs to be the same size as 4' fluorescent tubes either. That
whole business of making LED "tubes" the same size is just silliness
anyway. If one or two of them works OK for you, that's fine. I'm glad. But
it is not a lasting trend.

I suggest you look at the Cree products. That is what's coming. You could
mount several of those along a 4' frame and have a very nice setup.
Better light than the fluorescents because it is all used and not misdirected.
Intense too (100W equiv. each, I think) and maybe not as expensive, at
least comparatively, as you may think. If I were to try now to build what
I already have (6 tubes for each shelf), I'm sure they would cost well over
$200 for each unit. And I can't even do that because the parts needed
just cannot be had!

Whatever you do. I wish you good luck and great growing.

[Harry Cabluck]

This may be worth a looksee for those interested in LEDs: https://fluence.science/blog/redefin...ewsletter-2018

[biscuitridge]

Thanks so much Bower, that info is right on!

[bower]

This thread is really useful for anyone looking to choose new lights. Just a quote from the work that Harry C posted:
“Wavelengths are synergistic. The best analogy I can use is a balanced diet,” says Bugbee. He explains that a robust component of various wavelengths both within and outside of PAR allows greater rates of photosynthesis than narrow-band spectra, achieving an effect that’s greater than the sum of the parts. “You have to have all the nutrients for proper growth.”
So I do believe that in future there will be more of the "sunlike" full spectrum products on the market and those ugly pink/purple things will be a thing of the past.

Next thing we'll be talking about is how to avoid damage to your eyes.

[clkeiper]

actually this is exactly what I have been wondering while trying to replace bulbs in my grow light system. I inherited one of those 3 shelf 4' fixture systems a few years ago and the lights and ballasts are dying. so, I bought a couple LED grow lights at Menards and bypassed the ballast on the one fixture. then someone mentioned Walmart has the bulbs so I went and got a few but they are not bypass bulbs. sheesh! the question in my mind though was should I leave a white light and an LED on the same shelf and can I insert one of each bulb in the same fixture since I don't have to bypass the ballast for the LED....each shelf is two light fixture with two bulbs each.

[Greatgardens]

I had a similar experience at Home Depot. They had Philips bulbs that supposedly were "plug and play" But not to be -- returned them and bought bypass bulbs from Amazon. I like them a lot!

[zendog]

I bought a few bypass bulbs on Amazon, but they were inconsistent in terms of working in some of my fixtures and not the others. I went ahead and took out the ballasts and rewired the units and am glad I did. The bulbs look brighter to me, although I have no before and after to compare. But the big thing is that the fixtures are now so much lighter, making it much easier to adjust them up and down.