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time to find out - hid vs led

Posted by wordwiz (wordwiz@fuse.net) on
Thu, Jun 3, 10 at 22:44

Next week, I will be getting a 400 watt MH conversion bulb so I determine the best system before the the indoor growing season begins. I want to determine the most efficient light to use. Efficiency will be defined as pounds of salable produce per kW.

The contestants:

On the east is a 125-watt LED panel, said to replace a 400-watt HPS. It features red, blue and orange lights in a 8:1:1 ratio. On the west is a 400-watt MH/HPS set-up from HTG Supply. The lights will be hung at a distance that allow me to cover the advertised growing area (about 3'from the floor) but plants will be set on whatever I can find to get them as close to the lights as possible without heat or a loss in Lux occurring.

The test plants will be two types of toms, a Celebrity (determinate) and Better Boy (indy). They will be grown in 4-gallon plastic buckets using Tomato-tone as the nuit. All liquid will be provided from a common container (a 35-gallon plastic can) so the pH and ppm will be the same. The lights will run from the same timer (13 hours/day) and the same air pump. They are in the same room, so the temps will be nearly identical. Both grow areas are lined with Mylar, though not all the way to the floor.

Have I overlooked anything?

Mike


Follow-Up Postings:

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RE: time to find out - hid vs led

Someone to pay the water and electric bill?

I'll be watching your results.
Hope the LEDs win. :)


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RE: time to find out - hid vs led

Interesting experiment Mike. I will be following your results. I love A/B tests they are the heart of knowledge. I always find that flat white is a better reflector than myler and does not make hot spots, but what the heck, it shouldn't make nuch difference. How do you block the light between light sources from interacting with each other? Good luck.

Nelson


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re: time to find out - hid vs led

Nelson,

I'll post pics of the set-up when the MH bulb gets here but what I did earlier this year was to set up two 1x2 8' boards from the ceiling to the floor in front of one wall that faces south. On the east wall, a bit north of the other area is the other "stage."

Hate to admit it, but I never got around to finishing the room. I lowered the ceiling to eight feet, removed all the plaster and slats (had to, the previous people had urinated on the walls and the smell would not leave) and insulated the ceiling and walls.

I'm trying to eliminate every variable I can except the type of lighting.

As an aside, I just discovered a light meter that measures PAR light and will calculate the Daily Light Integral, which could (excuse the horrible pun) shed a lot of light on why I achieve the results I should. Alas, only one company sells them and they require a person to buy them in sets of three. Not a bad price - $190 but I only need one of them, especially for an indoor grow.

I know that if I run the MH light for 16 hours a day at the recommended height I'll get 30.8 mols/day. That's plenty of light. But I don't have a clue how many mols/day I will get from the LED if I place it at the recommended height.

Mike


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RE: time to find out - hid vs led

I like your methadology for the most part but the sample size is a little small for a good accurate result but you sure as hell will get a good idea. 10 plants under each would be better but your test is very viable as is.

I hope it goes well and good luck.


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RE: time to find out - hid vs led

Nelson,

You are 600 percent right! I should have room for six plants under each light but simply didn't start enough seedlings. And I don't have 12 4-gallon buckets.

But you have given me food for thought. I have enough Legend tomato seedlings to provide two per light so all I would need is two of another preferably determinate variety. I can use 5-gallon buckets for some of them and adjust their height from the light. But I would prefer to grow them is the same size buckets so I may try to go with four per light.

But yeah, the more plants, the better the data.

Mike


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RE: time to find out - hid vs led

Hi Mike

Acouple of messages ago you said you found a source for par meters. Always wanted one. Could do away with my old 50's camera meter that has served me well. Was it 190 for all 3 or $190 each. If it is $190 for all three, I would certainly buy one of them all we would need then is a third. Anyone interested. Light meters are great to have for spotting pattern, comparison, hot spots, dull spots and getting a good read on what your lights are doing. Par meters are the best because they measure in the photosynthesis range.

Nelson


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RE: time to find out - hid vs led

Nelson,

They are suppose to measure PAR light as well as Daily Light Integral - amount of PAR light the plant gets in 24 hours. They are from SpecMeters - the LightScout DLI 100 (I think - google LightScout and you should find them).

I talked with a rep today and he did tell me that there is not a conversion factor for LED lights. Bear with me: as Spectrum meters go, this in not that great. Good ones costs hundreds of dollars and I've seen some that once you add in the various sensors for specific wavelengths, they can be in the thousands of dollar. The way I understand it, this one operates as a basic light meter (measures all light wavelengths) then is calibrated to display the intensity of light between 400-700 nm based on sunlight. It also has a conversion factor for MH and I think fluoros.

IMO, having a light meter is as necessary for successful growing under lights as having a pH meter if one is doing hydro.

I hope to start growing this evening. Need to move some electrical cords around, fill the pots with water, rinse the potting mix off the roots, add the rocks, etc.

The MH light is giving me 40,000 lux at what I suspect will be the top of the plant. Letting the lights run for 14 hours per day will provide 28 mols/day.

I'll go on record now: to be successful the Celebrity and Better Boy plants need to provide at least 25 pounds each of tomatoes in the next 120 days. I would be thrilled if the Legend does also, but I'll take 20 pounds since they are older plants and have grown up outside for the last month (in a 3" nursery flat!). I don't have a clue how much cotton to expect - enough to make a shirt?

I'm off to start on it!

Mike


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It has started!

One each of Celebrity, Better Boy and Legend tomatoes, two Nankeen Cotton plants under each light.

Same nuit solution, same air pump, same size containers. Same air temps, plants in their own area where no light from the other one can affect the other one.

One thing that surprised me it hot much hotter the MH bulb is compared to the HPS.

Updates will follow!

Mike


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RE: time to find out - hid vs led

Hi Mike

I have had a lot of trouble with 24 hour light cycle from tip of leaves turning brown and dying all the way to total plant death. I have had no such problem with 18 hour daily cycle. I have my experience of course with pot plants and not tomatoes.

I have tried making the 20 hour day happen with my own designed timer. That is 16 hours on and four hours off. If you are trying to speed things up you could consider that for the tomatoes. Of course maybe tomatoes are not snsitive to having a dark period which seems to set the day cycle for the plant. Just an idea to consider.

Nelson


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RE: time to find out - hid vs led

Nelson,

Maybe you mis-read? Fourteen hours per day, not 24!

I did read a couple of studies, and one guy did a test last year, that showed running lights for 24/7 for a few weeks is beneficial but I think that was with low-power bulbs. After a few weeks, though, necrosis set in.

Mike


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RE: time to find out - hid vs led

I reread and you are right I did missread. Sorry about that.

Nelson


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RE: time to find out - hid vs led

No problem. Most growers use a 12, 16 or 18 lights-on cycle.

I figure using 14 hours ought to be more than enough, at least until the plants start blooming.

Mike


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RE: time to find out - hid vs led

It's only Day One, but I've noticed a couple of things:

The Better Boy tomato plants seem to have a hard time getting acclimated to water. Both are still very wilted, though I don't know why they would behave differently from the Celebrity. Both grew up under the same light, were the same size, are under the lights in the same place. The plants under the LED light seem - and it is very early - to be a tad more leggy than those under the MH. The exception is the cotton plants; those under the LED seem to love it. The Legend tomato plants, that have spent the last month outdoors, seem to be adapting well. They have become a lot more green in just a day.

I added a small fan to each set. Not exactly the same, but close. One is a converted 1500 watt heater whose heat wire was disconnected. The other is a 1200 watt heater that has a fan only setting. I figure it will make the stems a bit stronger as well as help dissipate some of the heat from the MH bulb.

I'll be on Cloud Cuckoo if I get 120 pounds of toms from the six plants!

Mike


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RE: time to find out - hid vs led

Hi Mike

If your experiment is successful I think I will seek your advice to set up some LED lights and try a pot plant. I don't know about flowering end, which requires about 3 to 4 times as much light as the growing, but vegatative groth has to be about the same requirements as a tomato. I know of one other person who uses LEDs for cloning with good success.

Before anyone gets too excited I will remind everyone that I am a licenced Health Canada grower.

Nelson


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RE: time to find out - hid vs led

An update:

Somewhat of a setback but perhaps a blessing in disguise. The Better Boys and Celebrity died. It looks like I broke the stems trying to get them in the net pots. So I am being forced to learn how to start them in rockwool, which is better (if I can do it).

The Legend tomato plant under the LED has a larger internodal distance while the MH Legend is more compact and a bit bushier. But the cotton plant under the LED looks stronger than the MH counterpart.

At least one and maybe two seeds have germinated so far. Once I see roots growing from the bottom, I will add them to the buckets.

Mike


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RE: time to find out - hid vs led

After some thought, I have decided to add an experiment within the experiment. Since I have four stations open and at least four plants the same size and variety, I decided two of them will be grown in my own nuit solution and the other two in EconoGrow/EconoBloom. Of course, one each under each light.

I feel I owe it to myself to see if store-bought nuits are better. Plus, this cannot impinge on the integrity of the test since I will make this batch of nuits and then divide it between the two buckets.

Mike


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RE: time to find out - hid vs led

The most important factor - what are the wavelengths of the LED's? What's you're seeing between the tomato and cotton is the reaction of each plant to limited wavelengths. That's been the hardest issue for people to get their heads around about LED's - different types of plants react very differently when the spectrum is limited. So you either need to determine the spectrum requirements of a specific species, perhaps even variety, and tailor the LED's to match, or just be sure to hit the 470 and 660nm peaks and include some cool/neutral/warm white's to cover the "micro wavelength nutrient spectrum". But even with the exact spectrum covered, total lumens is still critical, though the numeric value would be lower than a comparable white light. Of course, spectrum requirements may change over the life of a plant as Nelson mentioned - and there are some 40W LED's out now...


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RE: time to find out - hid vs led

It's only been a little less than five days since transplanting but I can see a noticeable difference. The seedlings under the MH are 1/3 bigger than those under the LED. Of course, a lot can happen in 90 days!

Mike


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RE: time to find out - hid vs led

OK, a week of growing. The plants:

This is one of the plants growing under the LED panel

And its sibling under the MH:

The other two. First, the LED:

And the MH:

Looks like the MH is far ahead!

Mike


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RE: time to find out - hid vs led

Why does the 3rd plant looks alot greener than the 4th?

My Tomato also seemed alot deeper green than my brother's, my secondary plants in dirt, rather than DWC, just abit more advanced than the pictured ones also seem to be burning vegetation-rubber compared to the sun grown varients.

My Money is on the MH if its similar in Lumens to the LED, otherwise I'd bet that those grown under LED's might not do so well, but will yield a smaller product, but longer.


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RE: time to find out - hid vs led

It's now been two weeks since the plants went into their buckets. I almost feel like I ought to unplug the LED to put it out of its misery. There is simply no competition, both in size and quality of the plants. I'm wondering if I ought to try one or two 105 watt CFL bulbs to see if I can get tighter nodes, then switch to LED once they start flowering.

Here is the page.

Mike


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RE: time to find out - hid vs led

I did. Turned off the LED, plugged in a 105 watt CFL on Thursday. Can see a big difference already. Better growth, tighter nodes.

Mike


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RE: time to find out - hid vs led

But without telling us some details about the LED lights, you haven't really told us anything particularly useful. Wavelengths, distance to plants, etc.


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RE: time to find out - hid vs led

zathras,

Why wait until now to post questions about the test?

I'll have to try to find out the specific wavelengths of the bulbs; more than likely the same ones you'll find on most basic LED lights.

As far as distance - about 12" from the light to the top of the hydro bucket. The seller claimed it will replace a 400-watt HID system, so I set it to a height that would cover a 3' wide area, then raised the buckets up high enough to still be covered with light.

Too much red and orange, not enough blue - no matter what the specific wavelength is.

But it may work great for fruiting!

Mike


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RE: time to find out - hid vs led


Why does the 3rd plant looks alot greener than the 4th?

Same reason the first is greener than the second. The pictures were taken under different lighting which effects the cameras color.

Mike are you going to try the LEDs again when the plants get large enough for fruit?


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RE: time to find out - hid vs led

taz,

Yes. Once they look like they are getting close to blooming I'll turn the LED back on.

Mike


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RE: time to find out - hid vs led

Update. One of the MH plants has exploded in growth this week. Not sure why - the one beside it gets the same light, nuits, etc. But it is 1/3 taller:

Here's its mate:

These next two are now under a 105-watt, 5000K CFL bulb. Actually, beside one! I wanted to get as many lumens as possible to minimize stretching. I rotate the plant each day.

And its mate:

All these plants were put into their container on June 23.

Mike


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RE: time to find out - hid vs led

I'll bet the taller one struck a couple new roots.


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RE: time to find out - hid vs led

Just this morning I noticed pre-blooms on both MH plants. It will be five weeks from "transplant" which would be a hair ahead of schedule, but the seedlings were only about 3 weeks away from germination.

Mike


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RE: time to find out - hid vs led

When you are growing with hps, you get a set of day/night differences.
1. 10-15 degrees difference in ambient temperatures.
2. No radiant heat hitting plants at night.
3. Relative humidity will change at night due to lower ambient temps.

You get these three differences just by turning the hps OFF for the dark period.

When growing with LED only, you do not benefit, as much, from these differences, because LEDs emit no heat.

It is these differences people have been overlooking...now we need to add heat, or another factor, to replace the lost differentials, when switching from hps to led....

This is why you see more apparent growth, as you ad more watts of LED; you are adding more heat to your day period, thus creating these differentials.


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RE: time to find out - hid vs led

From all I read, the small differences in temperature (the HID lights have a fan blowing on them and the hot air can rise) will not add but maybe seven Growing Degree Days per week to the HID plants. The reason one sees better growth with more LED wattage is because of more light intensity, more PAR photons hitting the plants. However, it is not a balanced spectrum, since most LED panels have 2-5 different spectra, not the 300+ MH or HPS, or even CFL bulbs do. My test was based on a 125-watt LED the manufacturer claimed was equal to a 400 watt HID system. It plainly wasn't.

Mike


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RE: time to find out - hid vs led

Like to make a couple of comments on this test. Cheaper 125 watt LED's usually only draw 90 watts or so, with 125 watts of total LED bulbs. A better quality 125 watt light, would draw about 125 watts, but would use 200W worth of higher quality LEDs. There is a huge difference in quality and spectrum of units, and aside from bogus manufacturer claims, comparing a unit that likely draws 90W against an HPS system that probably draws over 500 watts with the ballast (not to mention heat removal) is not a fair test.

A fairer test would be a true 200W (with 300W or so worth of LEDs) of quality build against a 400W HPS would probably have the LED come out on top with the newest generation products. Without mention of the brand or any other LED info, we cannot draw any real conclusions with this test.


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