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Lower?

I have been meaning to ask you opinions on this one for thelongest time but I forgot :-(

The light is now 40 cm above the plant, I dont feel the plant will get nay higher at this point. Should I lower the light? 

 

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Replies (20)
    • I have this spec sheet from the manufacturer. I just dont know about this, and I dont feel like risking making a mistake at this point either. 

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      • Tent is 80 X 80  btw

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        • It would depend on the light but you should be able to lower it a little say 30cm. 

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          • sorry i use an app that lets me calculate the height by ppfd / lux. i think chubby is right set it at 30cm above the canopy. 

             

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            • I do what Mark does. Use an app on my phone to tell me what the ppfd is that the light is putting out. It takes all the guesswork out of the equation.

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              • I have to us the app, I dont think the manufacturer can estimate an accurate height because of the different conditions in each grow space and these new LED's will burn the hell out of a plant if your not carful. That said, I have very little natural ability for growing, I can kill a cedar tree, and I am sucker for any gismo that even claims to make it easier

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                • What is the wattage of that light? Knowing that helps

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                  • Be careful it can turn into a rabbit hole. For me the only thing I can count on is the PPFD map. I want at least 500 ppfd in the far corners without the middle being equal to a solar flare

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                    • Oh no, not another rabbit hole, lol. I just cant remember ever falling into any rabbit holes before the internet. Now it happens two or three times a week. 

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                      • So I used the app Photone and selected full spectrum LED since I believe that to be correct and I got a measurement of PAR of 890 PPFD. 550 or so at the corners. 

                         

                        I measured my vegative lights and the CFL-like light I use measured about 50-70 and a smaller 15w LED measured 1100+ as it was positioned over the plant, I raised the light 5-10 cm and it dropped to a few hundred. 

                         

                        All good then?

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                        • 16-18”  or 45-50 cm at there stage is where I would put them the light draws 200watts you shouldn’t be burning them at that height. At seedling 70-100 cm.

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                          • I would be surprised if it pulls a true 200 watts.

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                            • yeah I thought that was a little weird a light advertised what is actually pulls at the wall. 

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                              • I just measured and it draws 218 w. 

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                              • Just installed a s33 from ac infinity in my 3x3 it says 30cm from flower canopy in the instructions. 

                                Haven't checked it with a meter and it might be a cm or so high but plants seem happy

                                I will check it at some point, and fuss over it but I think it's in the ballpark, I'll see how the plants look tomorrow after a daily dose of photons from this fixture.

                                If they look happy, I will only change it as they stretch and keep it there. 

                                On the other hand if they look stressed or otherwise unhappy, I will move the light up just a bit let it go again and so on. Nothings exact just really close. At this point too I will start to check things on my app to see if the fixture matches up with the ppfd map they have for the fixture at various heights. 

                                This fixture runs at 240w  2.7 umol/j which is a good efficiency for a fixture of this wattage. Lumatek are good fixtures too. Your fixture is listed to draw 205W and is 2.5 umol/j efficiency.  Good deal. 

                                When comparing Apples these are the numbers wattage and efficiency. Reputation too. Someone had to use them first right? 🤔

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