max CMH wattage for 5x5 tent?

Discussion in 'First Time Marijuana Growers' started by ddenny, Feb 23, 2021.

  1. I have 4 315 watt CMH lights and a 5x5 tent. I was wondering if with a 200cfm fan I could pump out enough air to keep the tent from getting too hot or if I need to use fewer lights. The strain is peyote purple and the room the tent is sitting in will be around 65 degrees.
  2. probably need a bigger fan. my 8'' ac infinity runs at 60% for 2 315's in a 2.5x5 tent. so my setup is essentially half of what u r trying to do. that much light in a room will heat the whole room up. a lot. my 5x5 1000w tent vents to the basement and constantly pulls 65-67 degree air in and the tent still runs 72-74 degrees.

    The guy that said run 2 lights is just wrong. thats not enough to flower a full 5x5 properly.
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    my 5x5
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  3. I don't use tents. But can't imagine putting 4 315cmh in here. Hortilux says 3x3. I found that to be exact. U will fry them in my op. Even if u have the right airflow and temps. Plus u will use like 32 kw a day if on 20 hours a day 20210224_045133.jpg

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  4. half of a 5x5 (25 square feet) is a 5 x 2.5 (12.5 square feet) which is what i have. running 2 315's. plants are very happy. 50w per square foot. the perfect amount of light.

  5. I assume I should use 3 315 CMHS for veg and 4 for flower, but when I use 4 what cfm should i have to keep it cool enough? would 400cfm be enough?
  6. there is no straight answer to that. u just have to run the lights and figure it out. if your tent is in a bedroom you will need to vent the heat to another part of your house or outside and have cool air going back into the bedroom. or run a window ac unit.

    if i ran 4 315's in my grow room and didnt vent the heat outside the grow room, it would be well over 100 degrees in that entire room after 12 hours.

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