2x250w HPS or 1x400w HPS for 3'x3'x6' Tent?

Discussion in 'Lighting' started by masonwinston, Jan 29, 2011.

  1. Hi all,

    Looking at lighting options for a 3'x3'x6' Secret Jardin grow tent that I'm picking up. I'm leaning hard towards having three flowering girls in the tent at all times. So, I'm wondering if I'd get better light spread and penetration by using two 250w HPS lights, or just one 400w HPS. Growing method will be DWC.

    I've been reading Cervantes' Medical MJ Horticulture Bible, and I believe that he feels that using two lights distributes light better, especially towards the edges of the grow area, while the main colas would see a benefit from the area where one light's output crosses paths withe the output from the second light.

    Also, are there any dual-output 120v digital ballasts that I could use to power both lights, if I choose to go with the 2x250w route? I'm hoping that maybe there's a 600w digital ballast that'll power both and give me a little headroom. I think, in theory at least, that a little ballast headroom can't be a bad thing.

    This will be a flower-only tent. I'll be housing my clone mothers and clones in a separate box.

    What say you, grass masters? ;)
  2. I saw a post here somewhere where a guy had a ballast powering two hoods but dont remember where it is here on the forum. The more light the better, also have you looked into one of those big light hoods like the Raptor or Magnum XXL?
  3. 400w if you can keep temps down and all
  4. #4 masonwinston, Feb 1, 2011
    Last edited by a moderator: Feb 1, 2011
    On the topic of reflectors, are the Raptor/Magnum XXL type of mega-reflectors going to tremendously outperform more standard/inexpensive reflectors like the XtraSun from Hydrofarm in a smaller setup like mine? I was specifically looking at the 6" or 8" Xtrasun.

    Thank you both for your thoughts! :)

    EDIT: Now thinking about going with the 6" Xtrasun due to space and weight considerations.
  5. Just saw that your putting it in a 3X3X6 grow tent. Because of the size and wieght of the hood and air flow I would use this hood with a 400 or 600 watt MH/HPS ballast. Its light foot print is 4X4. The problem that I just saw with the bigger hoods is the wieght issue and how much wieght the tents mountings bars can support. I never used a grow tent but theres alot of things to take into consideration. In a tent that small even a Cool Tube reflector would work good and would probably be your best option due to limited space and wieght and room for duct work for cooling the light. Also I would look into doing a scrog grow.

    Hydrofarm - Hydrofarm RD6AC Radiant 6" Air Cool Reflector Unit (includes lens)

    Sunlight Supply, Inc - Horticulture, Lighting, and Gardening Wholesale - Sun Tube 6" Reflectors
  6. there is a lumatek ballast that is dual 600W mh/hps switchable/dimmable, but it is 240v, dual lights is great for even coverage, but you wont have the penetration power a 400 has over a 250, and the tents an easily support any of the equipment you will need to hang. i am using a 400w hps in a 2'x2' tent with a 6"fan.
  7. Lol, no one answered this man's question. I am actually debating the same thing right now, I am vegging with fluroescents and flowering with a 250W MH and a 400W HPS. I want to upgrade to 1 600W or 1 1000W HPS, or run 2 400W HPS bulbs. I am not sure what would be better though, I am thinking I am just going to run the 2 400W HPS and invest in better bulbs. I think that you should honestly run with 1 400W lamp with a nice bulb. The footprint might be better on the 250W HPS and most people get great results with them, but I feel that ultimately the 400W is the starting point to really upgrading your yields after you have dialed everything in, just like people say when they went from a 400W to a 1000W HPS for flowering they were very very shocked at the difference in growth. I say roll with 1 400W HPS.
  8. I just saw that Lumatek ballast last night unfortunately like you said its 240 volt. As for how much the tents top can support in wieght everytime I try to open up the specs on grow tents something in Adobe Reader online I get an error and it closes Adobe. The Raptor hood wieghs about 58 pounds not including the bulb and any additional wieght from duct work, the Magnum XXL wieghs more.
  9. 400 watt with a cool tube or euro hood, you will be perfectly fine
  10. 400 watt in a 3'x3' sounds prime if you were to put 2x250 it would get too hot but with the 4oo ur still gonna want good ventilation!
  11. For a 3x3 I would use a 600w with the most square shaped air cooled reflector you can find. I know you asked about 400 vs 2x250, but why do either when the 600 will outperform them both easily.
  12. I was at work before and couldn't post a longer answer. I'll elaborate now.

    Using more point sources of light can have improvements sometimes, but in your case it won't. A single light source will fill out a square 3x3 area just as well as 2 sources would. It would only be better to use 2 over 1 if your area was in a rectangular shape. So since light spread doesn't warrant getting 2 lights over 1, it simply boils down to getting the most lumens per sq ft and the most light penetration. A 600 watt HPS produces roughly 95,000 lumens while a 400 watt produces 55,000 lumens. For 200 more watts you get 40,000 more lumens and significant improvement in light penetration. The choice is easy for me. Get the 600 with a square shaped hood and you will be lovin it.
  13. When I first posted this question, I did consider adding a 600w HPS to the list, but I was afraid it would generate too much heat. After that thought, I checked the Secret Jardin website, and they advise 400w as a maximum for this particular (3'x3'x6') tent.

    This really is going to be a personal grow, I'm not interested in vending. That in mind, I decided that it wouldn't be worth the potential for fire or tent damage to seriously consider the 600w light. The difference in lumens is pretty drastic, and I'm sure that I'd get much better growth from the main stems, and better penetration/buds from the side and undergrowth sites.

    Am I thinking too conservatively here? Safety really is more important than an extra few grams at harvest, at least to me.
  14. If they reccomend max 400 watt light then they probably have a good reason to. I would go with a 400 watt digital ballast and a cool tube light if I was setting it up for myself.

  15. I checked their site. They have an "advised" lamp section, but no where did I see it say max. It's simply their recommendation.

    A 600 is just as safe as a 400. A 400 is a reasonable light for that area and it makes sense that they would recommend that, but it's not ideal. If you have proper ventilation and good ambient temps outside of the tent you will have no problems at all. The only reason you should go with a 400 is if you aren't willing to ventilate properly or you are unable to keep ambient room temps low enough, but if you have those problems you will have issues with the 400 also.

    Ideal lights for given tents are 2x2 - 400, 3x3 - 600, 4x4 - 1000, anything bigger would need multi light setups. Of course you can run lower wattage with no problems at all if you want to, but personally I'm a big believer in getting the maximum out of a given area.

    I know a dude who runs dual 600's in a 4x2 tent. That's a smaller area than a 3x3 and he's running 2 600's with no problems at all.
  16. I am happy with my 400 watt but if I did it again I would upgrade to the 600watt light from the start with a good vortex fan

Share This Page