Friendly advice needed

Discussion in 'First Time Marijuana Growers' started by Organicdreamin, Nov 28, 2014.

  1. #1 Organicdreamin, Nov 28, 2014
    18in * 38in grow cabinet. 150 watt light. 8 white widows, 4in carbon filter and fan. Natural airflow tunneled under cabinet 8 ft flow space before plant breach, any heating suggestions for airflow in wintertime?


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  2. #2 loki125, Nov 28, 2014
  3. #3 Indie-Kah, Nov 28, 2014
    Last edited by a moderator: Nov 28, 2014
    ^ what he said, with the exception of his wattage figure. What's "wanted" is to get as near 128K lumens/lux hitting every plant as possible, while dealing with your conditions. If a plant's a meter from your bulb, it's getting about 81% of what it's rated. At 2 meters, 75% (inverse square progression). Use of reflective hoods and materials alters this a *bit*, but to see how much, you have to know the efficiency of reflection, and calculate fall-off of intensity between bulb and reflective surface, apply the inefficiency value, then calculate the distance from the reflective surface to where the light hits the plant, and apply "fall-off" for THAT value (as if the light comign off the reflector was, itself, coming from an emitter).
     
     
    400 watts HID is about 32K lumens, you have approximately half a square meter of floor space. If your plants are 18 inches tall, and the hood is hung 18 inches over that, your plants receive in the neighborhood of 25,920 lumens/lux of direct light at the bottom. That small an area, most hoods will work very well, so add 75% again to that, and you can figure between direct light and the hood, you're getting in the neighborhood of 45,000 lux at the base of the plant.

    Reason for reduction in wattage from an HID is HEAT management. If you can manage your heat, more light is better.
     
    Small area heat management can be a total bitch, though. I'm turning off my fans during a 2 hour dark cycle in a tent in my garage, currently, and outdoor temps have yet to have dropped below 25 (F), yet the tent stays over 60, and 2 hours after the lights come on, if I don't have the fans running at at least half speed, it gets to around 80 in there, despite being below 50 for a high every day outside.

    That's working in a 500 cubic foot tent with a total of about 2250 watts true, "2580 effective" watts of light (more if you don't consider gaps in bandwidth from my LED augments). And an air exchange of 745 CFM with the fans at half power (replaces total air volume 3 times in 2 minutes).

    And I'm STILL falling short of "sunlight intensity" by a LONG shot.
     
  4. #4 loki125, Nov 28, 2014
  5. #5 Indie-Kah, Nov 28, 2014
    Can't argue the statement, as I said, just the difference between giving "this is the wattage you want" and "this is the effect you want, but these are the problems you might have getting them"

    Tell someone who doesn't know why they want a given wattage, it becomes "the way it's done", for them. Tell them why, usually people are smart enough to figure out the best way to approximate the effect in the conditions they have with the budget and capabilities they have, yes?
     
  6. #6 loki125, Nov 28, 2014
    Yes but in an 18 inch by 38 unless you cool tubing it and using ac maybe even co2 1000w is gonna be hard to control tho id rather use 600whps bulbs as there most efficient may e a 250w-660w dimmable ballast woukd work well amd depwmding on ambient temps change the wattage.

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  7. #7 Indie-Kah, Nov 28, 2014
    Again, can't argue that...need to move a LOT of air volume through it to control the heat of a 1kW HID in that space...and throwing an 8" WindKing on a tent that size and running it fast enough to draw out the heat will basically turn the tent into practical vacuum inside...lol.
     
     
     
    Honestly, I'm kind of surprised you didn't suggest he dump $400 into a pair of "200 watt" LEDs and a few little CFLs to augment them.
     
    And honestly, in his circumstances, that's probably how I'd go about it in order to deliver the most intensity of useful light with the least heat issue.
     
  8. #8 loki125, Nov 28, 2014
    Well no every one has $400 to throw at led which ppl still dont believe theu can work plus being a girst grow best tongrab a 250 or 400w see how you do and see if you enjoy growing then move up to bigger when ready learn to walk before you run :) i prob wouldnt use cfls at all prob use led and hps if i couldnt get 2 leds

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  9. #9 Organicdreamin, Nov 29, 2014
    Thanks indie. I've got the cabinet lined with blue board and double layered plywood. The 150 is A hps. And the room my cabinet is k&n does not have central eat and air. More so a shop like home carport. And I have the intake of tunnels outdoor air. That travels down my duct and under my wall per lines and travels approxamately 8 ft before going upward in the floor of my cabinet through several drilled out 3/8 in holes. Then it is met by just a small Walmart heat/grow light. Then goes to my fan which then breezes air to plants then up and out on opposite side of cabinet in the top through my Carbon filter. Without heat light and with light off. I can be at least 10 degrees warmer than outside conditions, but when below freezing with both lights I can stay around 55-60 any types for raising temp few more degrees


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