Is 400 Watts Enough For 9 Square Feet? POLL

Discussion in 'Growing Marijuana Indoors' started by SantaMonicaMtns, Mar 8, 2012.

  1. #1 SantaMonicaMtns, Mar 8, 2012
    Last edited by a moderator: Mar 8, 2012
    After doing some research, it looks like people can't agree on the point of diminishing returns for watts/square foot. Some say 50 watts per square foot, others 75. That's quite a bit in the cannabis world, in my opinion (50% jump).

    Currently, I have a 400 watt mh/hps in a 5 square foot tent (80 watts/sq ft), but I'm upgrading my tent to 9 square feet (44 watts/sq ft). There will be 6-7 plants in the new tent.

    I'd like to keep my power use manageable, if possible, and get a return on my investment proportional to harvest gains from the added light after this first grow.

    Thanks for the advice
     
  2. #2 herb ballistic, Mar 8, 2012
    600w per 1m x 1m or 3.5 ft X3.5 ft is the coverage
     
  3. #3 Jellyman, Mar 8, 2012
    There is no rule of thumb for watts per square foot, but it's a common misconception that there is. In the two-dimensional terms of square feet, let's say that a 400w HPS supports top growth over a square area roughly 2.25' wide; 5sq' @ 80w/sq'. An 800w will support the same level of growth over at least twice as wide of an area, or 4.5' x 4.5', because the light will reach about twice as far. You then would have 20sq' @ 40w/sq'. That 40w/sq' from the 800w lamp can grow the same quality per sq' as the 80w/sq' of the 400w lamp.

    When you start discussing a 3D area, the numbers go up even faster because the 800w can support taller plants than the 400w and yield even more per sq'.

    Assuming a roughly square area, your new 3'x3' grow space would perform best under a 600w, as I think Herb suggested. A 400w can be stretched that far with regular plant rotation or a light mover, but the increased yield will be offset by a lower percentage of the best quality buds. The potency of the best buds would likely also suffer.
     
  4. #4 herb ballistic, Mar 8, 2012
  5. #5 spacejerk234, Mar 8, 2012
    You should buy a 600 watt to throw in the new tent and use your current setup for veg. chamber
     
  6. #6 Bullistic, Mar 8, 2012
    600w will give you the most lumens per watt. Meaning it is the most efficient use of power.
     
  7. #7 SantaMonicaMtns, Mar 8, 2012
    I ordered the 600 watt. When you guys on here agree on something, I tend to listen.

    Thanks for the advice, and poll.
     
  8. #8 herb ballistic, Apr 5, 2012
    Now what bulb
     
  9. #9 tplat, Apr 5, 2012
    MH or HPS or both? For MH I buy the cheap Sun Pulse ones and for HPS I buy the Hortilux Super HPS enhanced bulbs. Also Bullistic is dead on about the 600 watt ballasts being the most efficient when it comes to watts of electricity used per lumen of light generated. But thats for a 600 watt digital ballast not a magnetic ballast. Magnetic ballasts run hotter and arent as efficient as the digital ballasts.
     
  10. #10 herb ballistic, Apr 5, 2012
    I run Agro blubs
     
  11. #11 arciem, Apr 5, 2012
    I'm running a 600w HPS/MH and this is my 3rd grow. I started out with CFLs then graduated to a 250w HPS/MH and finally settled on my 600w. I would have saved a couple hundred bucks by just going with my current setup to begin with. If you get a 600w be sure to run a strong fan and cool tube. My temps in a 3x3x7 tent top out at 86 if I don't keep it open and the AC at 70…
     

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