Now important is lumens

[wordwiz]

We had an energy audit done yesterday and I'm trying to get my head wrapped around all the terms. Watts don't equal light, as a 14 watt flourescent can put out the same amount of light (that humans see) as a 60 watt incadescent. They guy left some samples of 20 watt, 2700K CFL lights I can try in dimmers if I want. They are supposed to put out 1200 lumens.

Several web sites support the 2700K lights as being great for encouraging foliage and flowering. Since they are free and use very little power, I thought I would give them a try.

I also have as couple of 40 watt, 6500K fluorescents and a 40 watt narrow spectrum f-light I can use.

Unless we have one of those periods where the sun doesn't shine for three-five days in a row, I'll only use the light at most three hours a day, and that will be around Christmas time when the days are the shortest.

Does anyone have any experience using these types of lights to supplement natural sunlight?

Also, would it make sense to use 2700K lights until the plant is in full bloom, then use the 6500K to promote growth of the fruit?

 

[habman]

We had an energy audit done yesterday and I'm trying to get my head wrapped around all the terms. Watts don't equal light, as a 14 watt flourescent can put out the same amount of light (that humans see) as a 60 watt incadescent.

Fluorescent lights are more efficient then incandescent light.
So for the same amount of energy you get more light with fluorescent. For growing plants incandescent are useless they put out too much red and infra red light.

They guy left some samples of 20 watt, 2700K CFL lights I can try in dimmers if I want. They are supposed to put out 1200 lumens.

Several web sites support the 2700K lights as being great for encouraging foliage and flowering. Since they are free and use very little power, I thought I would give them a try.

A general rule is 30 watts/sq foot for high light level plants (peppers and tomatoes).

I also have as couple of 40 watt, 6500K fluorescents and a 40 watt narrow spectrum f-light I can use.

Unless we have one of those periods where the sun doesn't shine for three-five days in a row, I'll only use the light at most three hours a day, and that will be around Christmas time when the days are the shortest.

Does anyone have any experience using these types of lights to supplement natural sunlight?

I grew a chilaca with an 85 watts CFL and no additional light.
works good.

Chilica pepper

Also, would it make sense to use 2700K lights until the plant is in full bloom, then use the 6500K to promote growth of the fruit?

No, use the 6500K for veg and 2700 for flowering. Personally I disagree with the 2700K being better for flowering. I think this comes from the pot growers that are obsessed with the flower size but for pepper growing it doesn't make a diffrence. The 2700K light will make the plant grow taller.

 

[QuebecFire]

I agree LOL I was growing pot (hehe sweet Quebec )with these lamps and I was obsessed of the flower size but now I stop to grow pot but i grow pepper (a lot safer) LOL but one thing I've lurn it's more lument you have more fruit you'll get ..more your grow room is smaller and light reflecting more fruit you'll get and the reflector may change the result to ...and agree with habman 6400 is for seedling and vedge state and 2700k is for bloom ....and if you want my opinion the best lument rate for price is HCFL (like Envirolite ecolight smartlight ect ..) just chec on the net or on ebay they are very cheap . personalu I have a 250w High Compact fluorescent and i work very well !and use very small qtt of power for lot of lumen! if you have any question pm me ,it's gonna be a real pleasur to reply

 

[wordwiz]

A general rule is 30 watts/sq foot for high light level plants (peppers and tomatoes).

Wow- This doesn't make sense. If I have a growing area that is 10 foot long by 4 feet wide, at 30 watts/sq.ft., I would need 60 CFL lights (at 20 watts/1200 lumens per bulb) or nearly 100 (at 13watts/900 lumens). Not only would I need some real good sunglasses to walk in the room, so would my neighbors if they look at my house.

But it comes back to my original question - how important are lumens? In the above example, the 13 watt bulbs would produce 90,000 lumens while the 20 watt bulbs produce just 24,000 lumens.

I guess the goal should be to mimic the natural, direct sunlight of a sunny day, both the spectrum and lumens.

 

[QuebecFire]

lol wordwiz ....never dude never !!! ----the 13 watt bulbs would produce 90,000 lumens --- a 13 watt cfl = maybe 900 lumen dude !!! my 250 High compact fluorescent have an output of 20 000 lumen and with a parabolic refletor = aprox 30 000 lumen

look :
HPS(high Pressur Sodium):
*150w ---> 14500 lumens
*250w ---> 33000 lumens
*400w ---> 55000 lumens

cfl lamp:
*125w ---> 10000 lumens
*200w ---> 17000 lumens

with a 10x4 grow room you'll need maybe a minimum of 2 or 3 200w cfl with square refletor and you may put your light at 1 or 2 inches of your plant !!

 

[habman]

Wow- This doesn't make sense. If I have a growing area that is 10 foot long by 4 feet wide, at 30 watts/sq.ft., I would need 60 CFL lights (at 20 watts/1200 lumens per bulb) or nearly 100 (at 13watts/900 lumens). Not only would I need some real good sunglasses to walk in the room, so would my neighbors if they look at my house.

But it comes back to my original question - how important are lumens? In the above example, the 13 watt bulbs would produce 90,000 lumens while the 20 watt bulbs produce just 24,000 lumens.

I guess the goal should be to mimic the natural, direct sunlight of a sunny day, both the spectrum and lumens.

30 watts/sq foot is correct.

Lumens are not a good way to evaluate the light needs of plants.
Lumens is a measure used to quantify the sensitivity of the human eye to different wavelengths of light.
The human eye is more sensitive to yellow and greens light.But plants use mainly blue an red light which rate poorly in lumens.
A better measure is PAR or Photosynthetically Active Radiation.
It measures the 400 to 700 nanometers wavelenght that is useful to plants for photosynthesis.
Unfortunately almost no light bulb, even the specialty grow light, give the PAR rating.

90 000 to 120 000 lumens for a 40 sq ft growing area is a good estimation.

Like QuebecFire said you got some numbers wrong.
20 watts bulbs produce about 1500 lumens not 24 000 lumens.

 

[koolguymike]

habman is right that lumens really isnt what you should be looking at but it is the best number you can come up with for lights, as a comparison. most dont give the this the that etc...


and another thing to remember, 10,000 lumens at the bulb IS NOT 10,000 lumens 3 feet away from the bulb.

and to me it sounds like quebecfire knows what he is talking about

 

[wordwiz]

Unfortunately almost no light bulb, even the specialty grow light, give the PAR rating.

The closest thing is have been able to find is a statement that basically claims all of the light is useable for plant growth (talking about the 2700K lights)

Like QuebecFire said you got some numbers wrong.
20 watts bulbs produce about 1500 lumens not 24 000 lumens.

He didn't read the first part of my post or forgot it by the time he got to the end.

According to the spec sheets, the 13 watt bulbs produce 900 lumens, the 20 watt bulbs 1200 lumens (the former are 6500K, the later 2700). The 24,000 lumens was the total of using 20 20-watt bulbs.

As I have only one plant close enough to require transplanting, I figure I'll start with one bulb and then add more as the number and size of plants increase. Also, the plants are getting 11 hours of natural sunlight now, though that figure will keep drop by several minutes per month.

 

[Skyjerk]

HID lighting (HPS or Metal Halide) produces far more light (lumens, foot-candles) per watt than CFL or fluorescent.

My HPS lamp produces around 140 lumens per watt, while a CFL lamp might give around 60 lumens per watt

So 400 watts of HPS lighting in my 5x4 grow room will give me about 2800 lumens/sq ft
while 400 watts of CFL lamps will give me 1200 lumens/sq ft.

Using the formula of 30 watts/sq ft, my 4x5 grow room needs 600 watts of lighting.

600 watts of HPS lighting will give me 4200 lumens/sq ft

600 watts of CFL lighting will give me 1800 lumens/sq ft

Given the huge disparity in light output for the same wattage, how can one reliably state light requirement for a given area in watts?

 

[scarecrow]

Sky, wanted to ask you how are your plants doing? any better from week ago?

 

[Skyjerk]

Sky, wanted to ask you how are your plants doing? any better from week ago?

Hey Scarecrow

Actually yes, they are. Not perfect, but looking much better.

I wish I could say which specific thing made the difference. Its possible that they were still recovering from previous problems and just had not perked up yet.

Initially I know I was watering them too much and they also had way high nitrogen. Maybe I fixed the issue a few weeks back and it just took some time for them to recover.

I also started watering them with collected rain water rather than tap water.

Anyhoo, things are lookin up.

 

[habman]

Using the formula of 30 watts/sq ft, my 4x5 grow room needs 600 watts of lighting.

The 30 watts/sq ft is just an approximation used for fluorescent lighting.

Given the huge disparity in light output for the same wattage, how can one reliably state light requirement for a given area in watts?

You are reducing light to lumens/watts. Not good.

Watts is not perfect but better then lumens to approximate the light requirement.

If you are convinced that lumens is a good measurement, then explain how a 50 000 lumen 400 watts hps can be outperformed by a 400 watts MH with 29 000 lumens.
You can't in terms of lumens. Lumens are not a good measure of light requirement.

Both the 400 watts HPS and the 400 watts MH will give good results (because you are providing 400 watts of light energy to the plants) but the MH will be superior.
The plants under the MH will have more pods and look similar to plants grown outside ( better PAR, light quality ).
-->>Lumens are not a good measure of light requirement.

 

[Skyjerk]

Understood, and agreed too, actually.

However, you misunderstand my post.

I wasn't actually attempting to argue that lumens was a good measure.

Merely that, given the huge difference in light output per watt between HPS and CFL, that watts cant be a reliable measure.

A lumen is a lumen no matter the wattage or type of lamp its coming from. It wont change.
A watt can produce a little or a lot of light depending on the type of lamp.

Lumens are absolutely not the best, but I would still bank that its more
consistent than watts.

PAR is definitely supposed to be good, but I have no way to determine my PAR needs or the output
of my lighting in those terms.

I also understand that HPS and MH have different spectral output.

I have enhanced spectrum HPS (more blue) and combine that with
5000k fluorescents to get a broader spectral range while taking advantage of the longer life of the HPS lamp

 

[scarecrow]

Hey Scarecrow

Actually yes, they are. Not perfect, but looking much better.

I wish I could say which specific thing made the difference. Its possible that they were still recovering from previous problems and just had not perked up yet.

Initially I know I was watering them too much and they also had way high nitrogen. Maybe I fixed the issue a few weeks back and it just took some time for them to recover.

I also started watering them with collected rain water rather than tap water.

Anyhoo, things are lookin up.

Good to hear sky, post some pictures sometime.

 

[wordwiz]

I keep doing more Googling and ran across http://www.sunmastergrowlamps.com/SunmLightandPlants.html

According to this site, a 400 watt MH light will emit 140 watts PAR. I read on another site that a 20 watt 2700K CFL will deliver 20 watts PAR. So for the same cost, I can run 20 CFL lights.

The same site (further down the page) say a plant that needs high level of light needs 75 PAR per sq. yard (though it uses meters). If this is true, then one 20 watt, 2700K CFL should provide enough light for 2.5 sq. ft. That's considerably less than 30 watts per sq. ft. as mentioned earlier.

Another site to read and at least consider is http://www.envirolites.co.uk/lightinfo.html

 

[scarecrow]

I keep doing more Googling and ran across http://www.sunmastergrowlamps.com/SunmLightandPlants.html

According to this site, a 400 watt MH light will emit 140 watts PAR. I read on another site that a 20 watt 2700K CFL will deliver 20 watts PAR. So for the same cost, I can run 20 CFL lights.

The same site (further down the page) say a plant that needs high level of light needs 75 PAR per sq. yard (though it uses meters). If this is true, then one 20 watt, 2700K CFL should provide enough light for 2.5 sq. ft. That's considerably less than 30 watts per sq. ft. as mentioned earlier.

Another site to read and at least consider is http://www.envirolites.co.uk/lightinfo.html

Sunmaster MH is very good light for plants.

 

[habman]

Very good find Wordwiz.
A fluorescent is approx. the same quality light then an MH.
So let's use the the numbers for the MH and we should get the value for the Fluo.


Let's crunch some numbers....


1 meter = 3.3 ft

1 sq meter = 10.89 ft

400 watts MH = 140 Par Watts

----------------------

Required Par Watts = 135 (very high light level plant)
Multiply by 1.5 ( because of light loss ) = 1.5 * 135 = 202.5 Par Watts * m-2

( 202.5 Par Watts * m-2 ) / 10.89 ft/m2 = 20.25 Par Watts / ft sq

Now let's calculate the efficiency :
400 Watts/ 140 Par Watts = 2.86 Watts / Par Watts

20.25 Par Watts / ft sq * ( 2.86 Watts / Par Watts ) = 57.915 Watts/ft sq for very high level light plant

---------------------------

Required Par Watts = 75 ( high light level plant)
Multiply by 1.5 ( because of light loss ) = 1.5 * 75 = 112.5 Par Watts * m-2

( 112.5 Par Watts * m-2 ) / 10.89 ft/m2 = 10.33 Par Watts / ft sq

Now let's calculate the efficiency :
400 Watts/ 140 Par Watts = 2.86 Watts / Par Watts

10.33 Par Watts / ft sq * ( 2.86 Watts / Par Watts ) = 29.54 Watts/ft sq for high light level plant

 

[wordwiz]

habman,

You wanna tackle photons next?

I don't know about the MH, but the CFL can go inches from the plants, so there is very little light loss.

Has anyone considered the effect of sunlighting for all but three-fours a day? My concern is "over-growing" them.

Years ago, when dad was raising tobacco, it was on someone else's land. We did the work and paid for everything except fertilizer. That was the responsibility of the land owner. Generally, he would get was was needed. But after a couple of years, he pointed out that weeds and other growth was staying green way longer than in surrounding fields - way, way, way longer. We were able to cut the amount of fertilizer by 1/4 and still get the same yield in terms of poundage (and actually, usually better quality).

Will delivering a lot more PAR watts for just those three or four hours make a significant difference?

 

[habman]

habman,

You wanna tackle photons next?

Photons hmm interesting.....

mol = 6.022×10E23
micro-mole = UMol = 6.022×10E17
Watt = 1 J/s

Plant energy requirement : 400 UMol m-2 s-1 based on 16 hour day of light

Let's calculate how many photons per day for 1 sq ft :

Day = 16 hours * 60 min *60 s = 57 600 s

400 * 6.022×10E17 / 10.89 ft sq * 57 600 s = 1274076033057851239669421 photons/ sq ft per day
---------
Converted to joules :

1 photon = 4×10–19 joules

1274076033057851239669421 photons/ sq ft * 4×10–19 joules/Photon = 509630 joules/ sq ft per day

-------
Let's calculate how many PAR watts / sq ft

400 UMol m-2 s-1 * 6.022×10E17 mol/umol * 4×10–19 joules = 96.352 J/S = 96.352 watts PAR /m

96.352 watts PAR /m2 / 10.89 sq ft/m2 = 8.84 PAR watts/sq ft
-------
Let's calculate the coverage of a 400 watts HID :

140 PAR watts / 8.84 PAR watts/sq ft = 15.84 sq ft = 4ft X 4ft effective lighting with 400 watts HID
----------
Let's calculate the coverage of a 20 watts fluorescent :

140/400 = 0.35 -> 35% of the lamp energy is converted into PAR light
we are assuming that a fluorescent light has the same efficiency then an HD to covert electricity to PAR light

20 watts * 0.35 = 7 Par watt

7 Par Watt / 8.84 PAR watts/sq ft = 0.79 sq ft


The info can be found here.Very interesting read.
http://ncr101.montana.edu/Growth_Chamber_Handbook/Ch01.pdf

ps I'm not trying to be a smart ass , I just find this stuff fascinating.

I've done lots of research this past year trying to figure out optimum growing conditions under artificial light.
I've done lots of experiment with different lights ( cost me a fortune but that's all the fun ).

-My conclusion is 30 watts / sq ft light is required.
-HPS alone is not optimal to grow peppers. HPS combined with a T5 54 watts pure actinic light 22 000K has very good results.
-MH is the best of the HID with the Hortilux blue being the optimal light source for HID.
-T5 54 watts work very well. The key when growing with fluorescent is to keep the plants the smallest possible so use lots of blue light.
-Use 6500k or better use the giesemann lights in combinations they are simply the best but expensive.
-Use a combination of aquablue and either aquaflora or midday for outstanding results.

http://www.giesemann.de/63,2,,.html

Will delivering a lot more PAR watts for just those three or four hours make a significant difference?

I think you will need to experiment.
Best way is to use less then add more if the results are not satisfactory.

 

[scarecrow]

Nicely put habman.
I will call you "Habman PHD" in plant lighting.