115 watts per square foot

Discussion in 'Growroom Setup' started by OregonsDank, Sep 30, 2006.

  1. OregonsDank

    OregonsDank Registered+

    I plan on using around 115 - 120 watts per square foot during bloom in a room 4x4 or 4x6.

    Is this way overkill for very high quality mary jane?
  2. tekneeqs

    tekneeqs Registered+

    As stated in one of the most thorough grow books, "Near 50w/sq. ft. a point of diminishing returns is reached, and the yield of the garden is then limited by the space the plants have to grow. For maximum use of electricity and space, about 40w/sq. ft. is the highest advisable".
  3. OregonsDank

    OregonsDank Registered+


    so just 1000 watt MH for veg , then a 1000 HPS for bloom
  4. tekneeqs

    tekneeqs Registered+

    that sounds perfect, as far as lighting goes.
  5. u.g.u

    u.g.u Registered+

    I run 50 wsf now but I remeber reading somewere that 75 was the point of dimishing either way 115-120 is way to much.
  6. BlueBear

    BlueBear Registered+

    75W is good, and yes there is a point of regres, but it is still a questionabl topic. Remember some serious growers are dropping a 1K light on one plant for tramendous results. Now if they put a 600W on the same plant who is to say that they wouldn't have the same or better results. But for a 4x4 a 1K is perfect in my opinion.
  7. Zandor

    Zandor Registered+

    The real questions are what the quality of the lights and color spectrum is. Plus it's more about par-watts or usable light to the plants.

    How many lumens and what color is a better way to look at your lights then just watts.

    Light coverage is just as important 1000w will be good coverage for about 4x4 but a 4x6 the ends will have less light.

    Just something to think about.
  8. qdavid

    qdavid Registered

    What Zandor said. If, for example, you use 4 cfls. Is the wattage really 4x150W (incandescent equivalents) or 4x42W (the real rating)? Lumens, color, and overall coverage of lights are the keys.
  9. harris7

    harris7 Registered+

    try not to use the incandescent equivalents. They dont mean anything, all they are is a marketing thing so people can replace the bulbs in their house and buy ones that are the same brightness. When we talk about HPS we dont say their incandescent equivalents because everyone knows they have higher efficiency.

    so, if you are trying to figure out the Watts/sq ft you must use the actual watts. and each different light as a different optimum. I prefer to use the lumens/sq ft.
  10. qdavid

    qdavid Registered

    Yuh, I know. I was just trying to explain by example. Maybe somebody else didn't know that. But thanks. Use your MG and HPS, but not everyone does use those types of lights. What was your question?
  11. Racerx

    Racerx Registered+

    Here is what I use. I have no overheating problems.

    4x3 closet with 1000 watt cooltube, pulled by a 200cfm squirrel cage and room is fed with a 150 cfm squirrel cage. Light spread is great. I get a very even canopy. 12 plants in 3 gallons

    4x7x4 box with 2 x 1000 watt aircooled lights, fed by a 6" 500cfm inline fan and exhausted (through the hoods) by a 750cfm inline fan. 50 plants (30 in planter box, 20 in 3 gallon pots).

    5x5 closet with 2 x 600 Digital HPS aircooled lights. Fed by oscilatting fan and passive intake (plenty for now, it doesnt get above 75 degrees in there), pulled by a 700cfm 8" Vortex fan through both hoods. 30 plants in 3 gallon pots.

    5x7x5 box with 1 600 Digital HPS for flowering, 25 plants in 3 gallon pots, and 400 watt MH + T5 Flurescents for 6 mother plants in 3 gallon pots on the other side. Exhausted with 500cfm 6" fan, intake with a fresh air 4" 250cfm fan near window.
  12. BlueBear

    BlueBear Registered+

    Ra Do you use any type of transformer or regulators for electric? What is the biggest headache with your set up? What kind of Oder control are you using?
  13. Racerx

    Racerx Registered+

    For everything but the 600 digitals I use standard 110v connections and I split them on the circuits so theres never more then 1500 watts on one circuit. I use nice surge protectors. For the 600 watt digitals, I run an electrical box that splits a single 240v connection into 6 240 volt connections. It uses a fairly standard 2 pole connector inside, the cool feature is that the connector is turned on and off via a normal 110v connection so you can hook a standard timer up to the box and not worry about running 40 amps through the timer or getting an expensive 220 volt timer. Running a 240v connection allows a ton of amperage through one circuit. More peaceof mind.

    I dont use any odor control in the cooltube closet except a little homemmade carbon filter that I dont think does much. For the larger areas, we use carbon filter scrubbers. So essentially its a standalone filter with its own fan, pulling air through the filter and then blowing it back into the air. It "scrubs" the air. A 6" filter about 3 feet tall can easily clean a 20x20 foot room if its pretty sealed. However I dont use any odor control until the last few weeks of flowering. Just never smells that much. I scrub the air where the exhaust is blown, not in the actual grow rooms. This reduces noise and increases space. There is so much air being sucked out of the room that it doesnt smell anywhere unless your inside the actual room.

    Biggest headaches is with the boxes and their height. Even with my 5 foot tall box, the largest the plants can ever get is 3 feet tall and lately my plants have been tripling in size easily during flowering. Our 4 foot tall box can only reach 2 feet tall (one foot for the hood, one foot between the canopy and hood). The boxes are more likely to get warm, but they are easier to control. Its been cold around here lately so my intake charges are nice and cool. If you have big overheating problems, sealing the lights and giving them their own fresh air intake will greatly reduce temps, but it requires more fans and more ducting. Otherwise, not really any big headaches. Humidity seems to be under control but I have a portable dehumidifier in case. I am a big fan of the cooltubes. They really work.
    Last edited: Oct 3, 2006
  14. oldnslow

    oldnslow Registered+

    A pal that ran a sog garden using hps did some experimenting with the lite intensity. He ran the same strain of clones in the same system for several crops. Lumens were 1-50w psq, 2-75 w psq, 3-110w psf. He said he didnt notice any difference in yield or growth beyond 50w psf, but managing the extra heat and elec usage were a chore.
  15. bejay

    bejay Registered+

    you should shoot for atleast 50 watts per sq ft dont really consider it overkill until you get over 80 but even then it could still be of benefit if your suppling side lighting to large plants even a 1000 watts over 1 7 footer isnt going to have well developed lower buds the light just cant penetrate that far, so would consider over 80 overkill unless you are doing it for large plants or a verticle scrog or someway of growing that you are using alot of the height of the room as per efficiency a grow room utilizing smaller plants and more of them is going to be more efficient as you will use less wattage for both veg and flower and have more harvest per year.
  16. BlueBear

    BlueBear Registered+

    Hey OregonsDank
    how is everything doing with your grow?
  17. OregonsDank

    OregonsDank Registered+

    Good so far :D

    Using 1000 watt MH in a 4x4 room with 6 clones in 3 gallon pots :)

    Pots are full of roots, but still havnt used up the initial water from when I transplanted, and plant height really hasnt budged , growing slow but strong - looks super healthy :)

    I think I shocked them a bit when transplanted due to lighting changes and other issues I got worked out, hoping they grow soon so I have somthing new to look at /tap foot :p
  18. SANDMAN187

    SANDMAN187 Registered+


    do anybody know a good spot for clones?
  19. tekneeqs

    tekneeqs Registered+

    Making your own is the best way. You'll need two weeks, a bottle of rooting solution (I got it for $6 at the local Home Depot), and finally a tray with dirt or something to root it in. There are many good threads with informative cloning techiques on this site.

    Anyhow, if you insist on buying ur clones then go to Hypropronic Shops and ask them, who knows, they might even have some in there.
  20. the image reaper

    the image reaper Registered+

    as stated earlier, after you reach 40-watts per square foot, the results diminish, supposedly holds true, ... but those 'equivalent wattage' figures on CFLs are hogwash, in my opinion ... I have a 500-watt equivalent CFL that isn't even close ... hope that helps some ... :smokin:

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