mobile Posted October 3, 2016 Report Share Posted October 3, 2016 The seller sent me details of where I can find the specification for the LED I have: https://cdn.shopify.com/s/files/1/0920/1206/files/Future_Eden_Full_Spectrum_PAR_Power_LED_380-840nm_Data_Sheet.pdf? Quote Link to comment Share on other sites More sharing options...
mobile Posted October 3, 2016 Report Share Posted October 3, 2016 The seller sent me details of where I can find the specification for the LED I have: https://cdn.shopify.com/s/files/1/0920/1206/files/Future_Eden_Full_Spectrum_PAR_Power_LED_380-840nm_Data_Sheet.pdf? 1 Quote Link to comment Share on other sites More sharing options...
Stu Posted October 4, 2016 Report Share Posted October 4, 2016 Just wanted to add that Michael Houlder at FutureEden is a great seller and will offer any help and advice on the LEDs if you ask. I got my 3W star LEDs from him and the service and quality was excellent. :) Quote Link to comment Share on other sites More sharing options...
mobile Posted October 4, 2016 Report Share Posted October 4, 2016 @Stu, it was Mickey, from Future Eden, who pointed me in the right direction for the datasheet I linked to above and whom I purchased the LED and lens from. Quote Link to comment Share on other sites More sharing options...
Yossu Posted October 5, 2016 Author Report Share Posted October 5, 2016 On 9/30/2016 at 10:26 PM, manders said: And another point. PAR 38 etc actually refers to the physical size of the bulb and has nothing to do with PAR as in the type of light produced. OK, so now you're confusing me again! I thought I'd got this sorted. So, back to the previous question, how do I tell a decent one from a duff one? We've established that the wavelength for red light is important, and that stronger individual LEDs are preferable to a collection of low-power ones (for the same apparent wattage), but what about this PAR business? Does that tell me anything? Please clarify for the permanently confused! Quote Link to comment Share on other sites More sharing options...
Yossu Posted October 5, 2016 Author Report Share Posted October 5, 2016 On 10/2/2016 at 10:17 AM, manders said: This is a complicated question. Plants use different pigments for a wide variety of reasons, as camoflage, as sunscreen, sometimes because they grow in dark places and utilise light of different wavelengths. Calatheas are a good example of the latter, they will grow where few other plants will, by reflecting red light back into the leaf from the underside they get a second chance of photosynthesizing the light which ordinarily would have passed through the leaf. Well, isn't that interesting! I have three Calatheas, and never knew why they had red undersides to the leaf. Thanks for throwing that one in. Quote Link to comment Share on other sites More sharing options...
Yossu Posted October 5, 2016 Author Report Share Posted October 5, 2016 On 10/2/2016 at 0:11 PM, mobile said: There is an article here explaining antenna pigments, which absorb different wavelengths and are used by photosynthesis: http://plantphys.info/plant_physiology/light.shtml This Emerson action spectrum graph, from the link above, demonstrates efficiency very well I believe: For those of us who are less versed in the technical side of this, please could you explain what this graph tells me? It's all a bit confusing really! Quote Link to comment Share on other sites More sharing options...
mobile Posted October 5, 2016 Report Share Posted October 5, 2016 15 minutes ago, Yossu said: OK, so now you're confusing me again! I thought I'd got this sorted. So, back to the previous question, how do I tell a decent one from a duff one? We've established that the wavelength for red light is important, and that stronger individual LEDs are preferable to a collection of low-power ones (for the same apparent wattage), but what about this PAR business? Does that tell me anything? Please clarify for the permanently confused! There is a type of lighting package referred to as PAR, which means 'Parabolic Aluminized Reflector'. Rather than me explaining it, it is probably better to look here: https://en.wikipedia.org/wiki/Parabolic_aluminized_reflector_light To confuse matters PAR can also stand for 'Photosynthetically Active Radiation'. Again, further details can be found here: https://en.wikipedia.org/wiki/Photosynthetically_active_radiation Growlights need to emit 'Photosynthetically Active Radiation' and they are sometimes supplied in a 'parabolic aluminized reflector' style housing, that really is the only link. 1 Quote Link to comment Share on other sites More sharing options...
Yossu Posted October 5, 2016 Author Report Share Posted October 5, 2016 Thanks for the clarification. When you first mentioned PAR, I looked it up and came across the Wikipedia article. I thought I was onto something then! So, it seems that the PAR bit in descriptions is probably a benefit, but overall misleading and useless for our discussions, as the main point of interest here is the wavelengths you get. Is that right? Thanks again. Quote Link to comment Share on other sites More sharing options...
mobile Posted October 5, 2016 Report Share Posted October 5, 2016 12 minutes ago, Yossu said: So, it seems that the PAR bit in descriptions is probably a benefit, but overall misleading and useless for our discussions, as the main point of interest here is the wavelengths you get. Is that right? Which PAR do you believe is useless in this discussion, the Photosynthetically Active Radiation or the Parabolic Aluminized Reflector? Quote Link to comment Share on other sites More sharing options...
Yossu Posted October 5, 2016 Author Report Share Posted October 5, 2016 1 minute ago, mobile said: Which PAR do you believe is useless in this discussion, the Photosynthetically Active Radiation or the Parabolic Aluminized Reflector? Sorry, my bad. I meant the Parabolic Aluminized Reflector. Perhaps "useless" was a bit extreme. It seems to be significantly less important that the wavelengths. Quote Link to comment Share on other sites More sharing options...
mobile Posted October 5, 2016 Report Share Posted October 5, 2016 32 minutes ago, Yossu said: For those of us who are less versed in the technical side of this, please could you explain what this graph tells me? It's all a bit confusing really! It simply shows what wavelengths are absorbed (used) in photosynthesis. You can see that there are peaks in the red and blue end and a trough in the green and yellow region. Quote Link to comment Share on other sites More sharing options...
Yossu Posted October 5, 2016 Author Report Share Posted October 5, 2016 1 minute ago, mobile said: It simply shows what wavelengths are absorbed (used) in photosynthesis. You can see that there are peaks in the red and blue end and a trough in the green and yellow region. Thanks. That I can understand! Quote Link to comment Share on other sites More sharing options...
Yossu Posted October 27, 2016 Author Report Share Posted October 27, 2016 Well, I finally got the two bulbs I ordered (linked somewhere earlier in this thread, but linked again for convenience), and I can't say I'm hugely impressed. For one thing, they don't seem that bright compared to the CFLs I'm using. I bought 36W LED bulbs, which are supposedly approximately equivalent to about 54W of CFLs. Doesn't look like it to me. Also, my trig was wrong, and the pool of light is only about 10" wide, which means I'd need quite a few bulbs to cover the same area as my CFLs. As it happens, one of the bulbs doesn't even work, which impressed me even less, but at the moment, I'm thinking of just buying some more 6400K CFLs. Thanks again to everyone who replied here, it was a great learning experience. Still learning, but not there yet. Quote Link to comment Share on other sites More sharing options...
mobile Posted October 27, 2016 Report Share Posted October 27, 2016 @Yossu, your eyes would not be the best measure of intensity. Do you have a smartphone, if so there might be a light meter app you could install, they are not the most accurate but would suffice for a comparison? Also, I strongly suspect that the supposed 36W LED lamp will not be running at that power. It is not uncommon for manufacturers to state the maximum potential power but omit to state the actual. 36W LED lamps are often made up of 12 3W LEDs, but it's rare that they are actually run at 3W as this would cause them to overheat due to inadequate heat management. Quote Link to comment Share on other sites More sharing options...
Stu Posted October 28, 2016 Report Share Posted October 28, 2016 15 hours ago, mobile said: 36W LED lamps are often made up of 12 3W LEDs, but it's rare that they are actually run at 3W as this would cause them to overheat due to inadequate heat management. Very true. Not only that but quite commonly with cheap LEDs (especially the 'cob' type), you may find that a few of the individual LEDs making up the matrix are broken/inactive. You'd not be able to see this with your eyes (blinded by the others), but if you photograph the light (on) and dramatically reduce the exposure on the camera/phone, you should be able to make out the individual bulbs and whether they are lit or not! Quote Link to comment Share on other sites More sharing options...
Yossu Posted October 30, 2016 Author Report Share Posted October 30, 2016 On 10/27/2016 at 6:40 PM, mobile said: @Yossu, your eyes would not be the best measure of intensity. Do you have a smartphone, if so there might be a light meter app you could install, they are not the most accurate but would suffice for a comparison? Also, I strongly suspect that the supposed 36W LED lamp will not be running at that power. It is not uncommon for manufacturers to state the maximum potential power but omit to state the actual. 36W LED lamps are often made up of 12 3W LEDs, but it's rare that they are actually run at 3W as this would cause them to overheat due to inadequate heat management. I tried a light meter app, and it showed the CFLs to output about the same amount of light as the LEDs, albeit with the CFLs spreading the light over a wider area (ie illuminating more plants at the same intensity). Given the size and cost of these bulbs, I can't see much benefit over CFLs, other than the supposed lower running costs. Not sure how much that would actually be a benefit compared to the significantly higher cost of buying the bulbs, and the fact that I would need more of them to illuminate the same area Quote Link to comment Share on other sites More sharing options...
Yossu Posted October 30, 2016 Author Report Share Posted October 30, 2016 On 10/28/2016 at 10:58 AM, Stu said: Very true. Not only that but quite commonly with cheap LEDs (especially the 'cob' type), you may find that a few of the individual LEDs making up the matrix are broken/inactive. You'd not be able to see this with your eyes (blinded by the others), but if you photograph the light (on) and dramatically reduce the exposure on the camera/phone, you should be able to make out the individual bulbs and whether they are lit or not! I tried using a normal camera, then used a photo editing package to reduce the brightness to almost zero, and all LEDs looked to be at the same intensity, so it looks like they are OK. Thanks for the tip anyway. Quote Link to comment Share on other sites More sharing options...
Martin7bergen Posted January 4, 2018 Report Share Posted January 4, 2018 Interesting thread, I was looking into Led light as additional winter lights in my greenhouse for pygmy sundews and mexican pings to help them survive our dark dutch winters. Maybe the following link maybe useful to some of you as well: http://www.ledgrowlightshq.co.ukVerzonden vanaf mijn iPhone met Tapatalk Quote Link to comment Share on other sites More sharing options...
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