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Thread: How Many LED's To Achieve 1,000 PPFD In 4x6

  1. #31

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    More air means more co2 available to the plants. True enough that the % of co2 in the air doesn't change. What happens is that the air touching the foliage is replaced quicker. So any co2 used by the plant is replaced quicker. Dutch growers came up with 'Fast Air'. 5 extractions per minute, which is 25 times the amount usually recommended.

    Blue61, at 27w psf, I don't think I'm going to have a problem with the amount of led light.

    This grow is with cmh and rvk. Next grow led and rvk. 3rd grow led and I've yet to decide what to do with the AC Infinity S4. Use it for extraction or get some elbows and tees and use it for internal airflow. I'm not against internal airflow in principle. I'm against unreliable oscillating fans or any other internal fans that get in the way. The S4 could sit on the floor out of the way and give me 4 columns of air blowing through the canopy.

    CHG, I have a 400w halogen heater. It gives off light but not enough to read by. A 600w hps will give plenty of light and some heat. To warm me up during a cold winter, I'd prefer the 400w halogen over the 600w hps. Watt for watt, more light = less heat.

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  3. #32

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    Quote Originally Posted by Farmer Geddon View Post
    More air means more co2 available to the plants. True enough that the % of co2 in the air doesn't change. What happens is that the air touching the foliage is replaced quicker. So any co2 used by the plant is replaced quicker. Dutch growers came up with 'Fast Air'. 5 extractions per minute, which is 25 times the amount usually recommended.

    Blue61, at 27w psf, I don't think I'm going to have a problem with the amount of led light.

    This grow is with cmh and rvk. Next grow led and rvk. 3rd grow led and I've yet to decide what to do with the AC Infinity S4. Use it for extraction or get some elbows and tees and use it for internal airflow. I'm not against internal airflow in principle. I'm against unreliable oscillating fans or any other internal fans that get in the way. The S4 could sit on the floor out of the way and give me 4 columns of air blowing through the canopy.

    CHG, I have a 400w halogen heater. It gives off light but not enough to read by. A 600w hps will give plenty of light and some heat. To warm me up during a cold winter, I'd prefer the 400w halogen over the 600w hps. Watt for watt, more light = less heat.
    Rule of thumb, A single watt of power is equal to 3.41 BTUs so a 600W luminaire will produce 2,046 BTUs.
    Wall-mounted oscillating fans are good to mix the air, your right about "co2 in the air doesn't change" but I replace the air before the plants can use all the co2.
    when I build my next flower room I going to use an 8" extractor fan, 6" intake fan, 2 wall mounted fans and a light rail.
    I like my flower room feeling like a windy day.

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  5. #33

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    Light is only too much if its too much for the system. 2500 ppfd is roughly the figure to cause damage. Garden plants seem to handle it most days perfectly well....

    The most overlooked factor is leaf temperature.

    HID irradiates the leaves with heat directly.

    LED does it passively via room temp.

    Forget all old temp numbers when cooking with led. This eliminates vast majority of calmag and spotting leaf issues.

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  7. #34

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    I much preferred using parabolics with 600w hps. In an open cab bedroom grow during warm weather, the room temps were 24'C and the canopy temps 27'C.

    With the grow I've just started, the seedlings were 25'C when my kitchen was 23'C. Even at 40% power the 8" rvk is shifting some air.

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  9. #35

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    Quote Originally Posted by gardro View Post
    Many charts available, I tend to read the scientific ones rather that led manufacturer ones. Be careful what species, cultivars and environment you are drawing any conclusions from.
    If you could post a link to the scientific ones that you use, it would be greatly appreciated!!

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  11. #36

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    Quote Originally Posted by Farmer Geddon View Post

    Blue61, at 27w psf, I don't think I'm going to have a problem with the amount of led light.
    Thats twice what I run (250w in a 4x4 gives 15w psf) and I have burnt my share of plants

    NO SELL, NO SMELL, NO TELL!!!


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  13. #37

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    Quote Originally Posted by Mac View Post
    Thats twice what I run (250w in a 4x4 gives 15w psf) and I have burnt my share of plants
    That sounds interesting. For my 2nd cupboard scrog when the leds are fitted, I should be doing my best to get a fair comparison with the cmh. There's a part of me though that keeps thinking: Bleach Baby Bleach.

    My 8" rvk is at the lowest I can run it, 40%. If my maths is correct, the conversion factor for m3/hr to cfm is 0.59. 960m3/hr = 566cfm. At 40%, assuming linearity, it's 226cfm. Not much more than the AC Infinity S4 @ 205cfm. The S4 can be turned down a lot. Plenty of opportunity to learn how much difference airflow makes.

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  15. #38

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    Quote Originally Posted by Farmer Geddon View Post
    That sounds interesting. For my 2nd cupboard scrog when the leds are fitted, I should be doing my best to get a fair comparison with the cmh. There's a part of me though that keeps thinking: Bleach Baby Bleach.

    My 8" rvk is at the lowest I can run it, 40%. If my maths is correct, the conversion factor for m3/hr to cfm is 0.59. 960m3/hr = 566cfm. At 40%, assuming linearity, it's 226cfm. Not much more than the AC Infinity S4 @ 205cfm. The S4 can be turned down a lot. Plenty of opportunity to learn how much difference airflow makes.
    I run my 4" AC on my 2x4x5 tent at setting 1 and it still sucks in the walls of the tent,haven't fitted my carbon filter yet might have to hit setting 2 lol

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  17. #39

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    Quote Originally Posted by Danniel Shoemaker View Post
    If you could post a link to the scientific ones that you use, it would be greatly appreciated!!
    Sure I will find a good one and PM you

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