Grow Lights

[JCO]

I took a look at their site and Yep, you're right...their tomatoes are a lot racier than ours...big time different market altogether

[Madmax478]

I'm kinda of curious to see how flowering and fruiting plant work under this LED light my self. That what I hear the big Beef is against LED lights. As far as leafing plants IMHO this one works well.

[urbanfarmer]

I have it 24 inches above the plants. I'm currently using it on about 1.5 sq foot grow bed. It is using Red, Blue, and Orange LED's very little light from a window and I don't often have the light on in the living room. Even though plant growth for this light is AWESOME the price is outside most people budget. I'm getting growth from a one month old system better than I would get off of a fully cycled 1 year old system. Haven't check out the performance on fruiting plants yet. I just got the light a day or so after I started this system up.
Here is there web site. You can go read there propaganda about there light. Just take into consider we are not there target market.
http://www.prosourceworldwide.com/

They sell these on eBay for less than half the price. I have looked at them in the past. The savings on electric compared to HPS/MH pays for the LED light itself; however, you can compete in that respect with fluorescent bulbs. I was expecting more than 1.5 sq ft since some of the advertised ones state as much as 16 square feet of space!!! I assumed realistically it was more like 4 or so based on comparing the advertisements and results on forums from folks. Very interesting stuff. Keep us updated!

[davidstcldfl]

Just take into consider we are not there target market.

I took a look at their site and Yep, you're right...their tomatoes are a lot racier than ours...big time different market altogether

I didn't see any pictures of tomatoes at their site...
?......when I went to the site and saw the prices.....'CLICK' the went on....You guys were talking about 'Those growers', the ones with the high cost product......


If the light last as long as they claim, they might not be bad for small setups inside to grow stuff like lettuce and herbs ( the kind found in grocery stores ) Between the electric savings and the 'life span' of the lights (about 6 years)...it might not be that costly over several years.

[cookie]

Long time reader first time poster here,

I have monkeyed around with lighting for a while and found T-5 far better then t-12 0r t-8. I would go with t-8 for cuttings and such as you can get the set ups close to the t-12 price and they give off more light per watt used. The t-5 outperform the others in lumen per watt its going to pay for itself fast as most people would run the lights 18+ hours a day.

Myself and others I know have found the LED lights out there lacking but the newer ones with 90 degree lenses on them instead of the wider ones seem to show promise. There is one company out west that gave some out to people to try that looked like the regular rectangular LED grow lights but had made in USA LEDs installed just shipped them there got them installed and then finished ones shipped back. I just look for the company but it looks like they went out of business. The ones they had seemed to do the trick over the UFO or chinese made LED types.

Experiments I tried along with others showed slow growth rates and overall poor fruit/flower development with LED lights tested but over all more material was harvested per kilowatt hour and over all watt amount of lights hanging compared to HID. That seems like a good thing until you see that plants may take a week or two longer under them to ripen so it might pay better to buck up to HID or high power florescent instead.

I did use some LED panels later as side lighting and that really helped lower branches as 600watt HPS from above would get blotted out after a foot or so of dense canopy.

To address the heights of lights I would always just keep whatever lights as close as I could hold my hand and feel comfy. Light intensity decreases x4 every time you double the distance so keeping them more then a foot away is just pissing away electricity. Get a mover or hook two bulbs to one ballast and wire a relay up to flipflop them just get them close. If its a little to close just back it up it will heal.

If you want to get 400 watters cheap look to craigslist and you will find high bay lighting that can be cheaply converted over by changing the plug and wiring the bulb remotely. Get a little sheet metal and bend up a hood or hang the bulb in the middle of taller plants sans hood for even greater efficiency. I think 600 watters where found to be the best for HID type as you can bring them closer to the plants then 1000 watt bulbs so it ends up putting more lumens to the veggies.

My next set up will be a mix of lighting but mostly t-5 maybe home made t-5HO as I would bend up the case myself and wire it as the parts might be cheaper separate. I have yet to price the t-5HO parts out but the t-5 ballasts, holders and bulbs come out way cheaper if you just make your own fixture. I plan on having some 400 watt MH on flip flops to help out as I have about 50 extra ballasts I need to do something with.

I have only done a small fish tank set up with aquaponics but have other experience with indoor farming and hope to go full scale soon aquaponic wise.

[Oliver]

Light intensity decreases x4 every time you double the distance so keeping them more then a foot away is just pissing away electricity.

This idea of inverse square law is a little misunderstood. It is actually the inverse square of the distance "from the light's theoretical point source".

For example, if you have a light array that is two foot square (four square feet) and has an aperture of 90 degrees, then the theoretical point source is one foot behind (above) the light's position. This is found by extending the light pattern to an intersection above (behind) the light. Or, just use trigonometry (tan function) to calculate its position. (1ft X tan(45deg))= 1 ft. The first 1 ft. is half the distance across the light. The 45 degrees is half the aperture angle.

So, if the light is one foot above the grow bed and radiating a given amount of light, then the point source is two feet above the grow bed. By moving the light to three feet above the grow bed the point source moves to four feet above the grow bed thereby doubling the point source's distance from two to four feet above the grow bed. The light intensity is now one forth and the area covered by this new intensity is four times that of the light's original one foot distance. You have moved the light from one to three feet above the grow bed and quartered the light received for a given area.

Starting back with the light at one foot above the grow bed, for an aperture of 45 degrees the new point source is 2.4 feet behind (above) the light of the same size. The new point source is 3.4 (1 + 2.4) feet above the grow bed. In order to double the exposed area you would have to raise the light's point source to 6.8 feet (twice 3.4 feet) or the light to 5.8 feet above the grow bed, thereby reducing the light to one forth its original intensity at one foot above the grow bed.

It is important with anything other than a single point source, such a a single LED, that the point source of the array be calculated in determining the amount of light and the area that is covered by that light when it is moved away from its target.

My example is for a square array, but if the array is not square or round, but instead rectangular like most fluorescents, then the calculations must be made separately for both dimensions. The aperture will be affected by the reflector behind the lights and will not be the same in both directions.

I realize that I have made this somewhat technical, but if you are serious about knowing how the lighting is changing with position then once you have a set of numbers you can then calculate what the change will be if you move the light.

Or, you can get a light meter and measure it. Be advised, however, that the inexpensive light meters are set for 550 nm or yellow/amber light. LEDs generally emit light at wavelengths other than what the meter can accurately measure. The more expensive light meters come with filters and have either correction tables or an adjustment to compensate for their change in sensitivity to that wavelength.

Oliver

[urbanfarmer]

Light intensity decreases x4 every time you double the distance so keeping them more then a foot away is just pissing away electricity.

This idea of inverse square law is a little misunderstood. It is actually the inverse square of the distance "form the light's theoretical point source".

For example, if you have a light array that is two foot square (four square feet) and has an aperture of 90 degrees, then the theoretical point source is one foot behind (above) the light's position. This is found by extending the light pattern to an intersection above (behind) the light. Or, just use trigonometry (tan function) to calculate its position. (1ft X tan(45deg))= 1 ft. The first 1 ft. is half the distance across the light. The 45 degrees is half the aperture angle.

So, if the light is one foot above the grow bed and radiating a given amount of light, then the point source is two feet above the grow bed. By moving the light to three feet above the grow bed the point source moves to four feet above the grow bed thereby doubling the point source's distance from two to four feet above the grow bed. The light intensity is now half and the area covered by this new intensity is four times that of the light's original one foot distance. You have moved the light from one to three feet above the grow bed and halved the light received for a given area.

Starting back with the light at one foot above the grow bed, for an aperture of 45 degrees the new point source is 2.4 feet behind (above) the light of the same size. The new point source is 3.4 (1 + 2.4) feet above the grow bed. In order to double the exposed area you would have to raise the light's point source to 6.8 feet (twice 3.4 feet) or the light to 5.8 feet above the grow bed, thereby reducing the light to half its original intensity at one foot above the grow bed.

It is important with anything other than a single point source, such a a single LED, that the point source of the array be calculated in determining the amount of light and the area that is covered by that light when it is moved away from its target.

My example is for a square array, but if the array is not square or round, but instead rectangular like most fluorescents, then the calculations must be made separately for both dimensions. The aperture will be affected by the reflector behind the lights and will not be the same in both directions.

I realize that I have made this somewhat technical, but if you are serious about knowing how the lighting is changing with position then once you have a set of numbers you can then calculate what the change will be if you move the light.

Or, you can get a light meter and measure it. Be advised, however, that the inexpensive light meters are set for 550 nm or yellow/amber light. LEDs generally emit light at wavelengths other than what the meter can accurately measure. The more expensive light meters come with filters and have either correction tables or an adjustment to compensate for their change in sensitivity to that wavelength.

Oliver

I don't understand your application of the inverse-square law... I think I'm getting the inverse-square law on its own... anyway, why are you treating a light fixture as 2 point sources?

I think the idea is closer is better, yes?

Light intensity decreases x4 every time you double the distance so keeping them more then a foot away is just pissing away electricity.

I think what cookie is misunderstanding is not the inverse-square law, but the concept of units. For instance, if we magically switch to the metric system, then by your implied logic the best distance is 1 meter, correct?

The Truth is 1 foot is NOT the optimum distance. The optimum distance the is the distance that maximizes the light usage for your plant, which will change as the plant grows.

The End!

[urbanfarmer]

[AQAUPONIC] SYSTEMS DO NOT WORK FOR GROWING MARIJUANA. We have a report from a friend of a student of ours, who had grown marijuana successfully using hydroponics for years, who tried for over a year to grow marijuana using Aquaponics systems, and never succeeded. Just so you know: When we say “food”, that is really what we mean.

SOURCE: friendlyaquaponics.com/do-it-myself-systems/micro-system/

[Oliver]

I don't understand your application of the inverse-square law... I think I'm getting the inverse-square law on its own... anyway, why are you treating a light fixture as 2 point sources?

I think the idea is closer is better, yes?

I'm not sure what your question is, especially about two point sources. I will attempt to clarify.

For a light array that has the same aperture angle in both dimensions (directions) then for calculation purposes, it is one point that is located behind the light fixture. That is the point that is used to calculate the inverse square law of the light's distance from an object and the effects of any light intensity change due to changing that distance.

For a very large light fixture array, one that is much larger than the area to be lighted, this distance (known as aperture near field) does not appreciably affect the amount of light being received by the plants until the change in distance is at least as far away as the light fixture array is big. From this distance and beyond (known as aperture far field), any increase in distance will affect the amount of light being received by the plants. This is why in a very large grow house, the lights can be placed high above the plants, and as long as you have ample lighting, the distance has little relevance. As you move further away from one light (due to its increasing height), you come into the beam of an adjacent light. The light array, in this case, is the whole top of the grow house. The point source then, is perhaps several hundred feet above the plants, thereby making any change in plant height irrelevant with regard to the amount of light being received.

When you have a point source such as a single LED, then the light is the point source, for there is no array of lights. In that case, yes, the closer the better, up to the point of over lighting the plant.

As an example, some species of lettuce do much better with less light over longer hours, which saves on electricity.

Oliver

[Oliver]

Oops,

I made a mistake in saying the light is reduced to one half the original value for a doubling of point source distance. I should of said reduced to one forth its original value.

I have made the correction in the earlier post.

Oliver