600w vs 400w on 64x20x36 grow tent

Discussion in 'First Time Marijuana Growers' started by smoosh, May 27, 2010.

  1. Hello,

    Well I have a 64x20x36 grow tent with a 600w hps/mh. I having temps in the 80F & 90F range. The normal room temp during the day is around 90F and 87F at night without a/c. I am thinking on buying a 400w to replace the 600w but before I do that I would like some info.

    I know 600w is overkill in this space but, replacing it with a 400w would make a significant change in temp considering normal room temp?

    What you guys think?

    Check out my journal for more info.

    Thanks! :)
  2. #2 benthamj49, May 27, 2010
    Last edited by a moderator: May 27, 2010
    You really need a cool tube / air cooled hood to remove the heat from your tent instead of letting it pile up in there. Your temps will drop to near-outside tent temperature. Here's a good, cheap, homemade tutorial: DIY Cool tube setup CHEAP. - The Garden's Cure

    And yes, it will make a difference, but not a big one unless you go with a aircooled facility of some type with a glass separator.

    Aim for temps: 70-83 max.
    RH: can be whatever for veg but low (30-50%) for flower.

    EDIT: I have that same size tent and I went all the way down to 250W from 600W (heat was a huge issue and with the way those plants stretched I would be fucked right now because I only have about 8-12" between plant tops and light at maxed out position) because 600 is way ridiculous. 250W gives you 50W/sqft 400W gives you 80W/sqft so I mean whatever you wanna do but it works with 250W and a cool tube. You can see my setup in my journal. My tent is just a little shorter than yours, 60x20x36
  3. If you provide enough cooling and ventilation, you can run the 600 in there just fine.

    Put the ballast in a remote spot (outside of where heat is an issue) And find a way to bring cool air in through the bottom and hot air out through the top.

    Is it possible for you to vetilate the hot air into an attic?
  4. i have a grow tent the same size with a 400w mh/hps light. and you will need to a hood vent because it does get pretty warm in there.
  5. I think you also need to cool the room....90 is too hot to provide any effective cooling to the tent. its hard to take them below room temp even with BIG fans. ac would be a huge help.
  6. #6 smoosh, May 28, 2010
    Last edited by a moderator: May 28, 2010

    Yea, I already have a air cooled hood connected to a high velocity fan. You can see it in my journal. ;)

    Yeap this also has been done. :(

    Well it is concrete. And I am not allowed. I am fucked right? :(

    Yeah this is what I mean!

    I can buy a 250w or 400w lamp but, would it make a difference when outside temp in the street and inside the room is around 89F during the day and 81F at night?

    Any ideas of approximately how many difference in degrees would I be looking at?

    Would it be a significant difference on my crop?

    Someone who knows better than me please give me your opinion.

  7. What are you max and min temps and do you use a/c?
  8. Sounds like you just need to use AC. Check Craigs List for portable ac units, you can usually pick one up for under $200.

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