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Thread: Upgrading HLG old 260 Light

  1. #11

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    When fitting the lights, I tried hanging them high it in case it worked, would be very convenient. I was half expecting it not to work.

    The inverse square law doesn't really apply to indoor grows. Spillover light bounces off the white walls and finds its way to the canopy. Meaning the plants get far more than a quarter of the original intensity if the height is doubled. In a groom, the intensity of light won't quadruple if the height is halved, the led charts show that. I used a darkroom light meter to check for variations in illumination corners to middle and it's as even as I could wish for.

    2 months in, I can say that not needing to alter the height of the light is joyously convenient. Previously, I've banged my head on lights more times than I can count.

    What got me thinking of hanging the light high was seeing the led charts. At 18", there is a large difference between middle and corners. Although the total intensity is lower at 24", the middle to corner difference is closer. There should be a height where the reflective walls even out the light hitting the corners and middle and has the groom acting like a parabolic reflector.

    For the same amount of illumination, more leccy used with a light hung high. (Assuming a dimmer is used.) Is having very even illumination and extra convenience worth that extra leccy? Hmm...

  2. The Following 4 Users Say Thank You to Farmer Geddon For This Useful Post:

    barney_b (16-03-22), Deku Nut (16-03-22), GEORGE (17-03-22), psy (16-03-22)

  3. #12

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    OK so I just did some basic testing with Photone iPhone PAR App. With this app my HLG 100 V2's are right at 20 PPFD of what most folks are testing these lights at with a Apogee sensor in my 3' x 3' tent. Good enough for government work. With both lights running at 27" above the tallest of four plants in the tent. Measured at the back two plants at the top 434 PPFD, front two plants are at 357 because the door is open, thus no reflectivity. With only one of the 100 V2's in the center of the tent those numbers fall a bit better than half to 200 and 120PPFD respectively @ 27". With only one light in the tent @ 60" over the tallest plant it would not even be worth firing the light up reflectivity or not.

  4. The Following 3 Users Say Thank You to psy For This Useful Post:

    barney_b (16-03-22), Farmer Geddon (17-03-22), GEORGE (17-03-22)

  5. #13

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    I don't see an HLG 100 covering 9 sft. If the tent is 1m square, that's 10.8 sft. My space is a little over 80cm square. 7 sft as best I can calculate it.

    I've had decent results in that cupboard using a 315w cmh. 45w psf. The door has light leaks, hardly noticeable if the hall light is on. After switching to 2 x HLG 100, the light leaks were brighter. With only 1 light on, the leaks still seem brighter then with the cmh.

    I'll know by the end of the grow is one light is enough. I'm tempted to plug in the 2nd light once the flowering stretch is over.

    I may have to accept the fact that I need a light with a dimmer.

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    GEORGE (17-03-22)

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