Ventilation question

Discussion in 'Growing Marijuana Indoors' started by Sweepcut, Jun 24, 2019.

  1. Hello, all, noob grower here, I'm stumped by a ventilation issue and wondered if any could help. I have a 4x4x8 tent with the hlg 550 v1 light and a 6 inch exhaust fan, but I'm finding that when I close the tent the 6 inch fan is not cooling the temp down enough. Does that make sense to anyone? I thought that 440 cfm exhaust fan would be plenty to exhaust the hot air given the lights and tent dimensions, but the temp just keeps climbing and the fan cant keep up. What should I do?
  2. What kind of temps are we talking? Soil or hydro? Do you have another pedestal or clip fan you can add in easily?

    Sent from Space
  3. Like up to 85, maybe hotter. I got a clip on fan circulating air. I'm just baffled as to why I cant keep the temp about 77 or so with a 6 inch exhaust fan and the tent closed plus a qb light. Everything I've read says 6 inch should move enough air. The tent is definitely having air sucked out, too--i can see the walls carving in.
  4. Also a noobie here, but do you have intake vents open for air to take place of the negative pressure? What is the temp of the exterior of the tent? I was told that plants don't like negative pressure as well.

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  5. Yeah I got the ports at the bottom open to let fresh cool air in. Outside temp about 75, but inside the tent its pushing 83 84 with the exhaust fan running at max. The tent temp just keeps climbing
  6. Are you drawing air in passively from the same room you're venting into?

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  7. Yes passive air intake from the same room but the room is large and the windows are wide open. Also, air is exhausted near the windows, so hot air should be headed out instead of circulated and trapped in the room
  8. Apparently that 6" fan isn't strong enough.
    Normally an intake fan is unnecessary, but you might need one to increase air flow.
    The faster the air flow, the closer temp/RH inside the tent will come to those values outside the tent.
    Increasing humidity up to the values given in the Vapor Pressure Deficit chart with a top fill ultrasonic humidifier will help a little, because the mist put out absorbs heat as the liquid droplets change to gas.
  9. Do you have a carbon filter? Ive noticed if you use a humidifier with hard water the minerals get left behind in the air in the form of a white powder which will quickly clog up your carbon filter and you won't get any pull
  10. You've given the reasons why an ultrasonic humidifier should never be used except with RO or distilled water.
    My top fill ultrasonic humidifiers use as much RO water as the plants do.
    The evaporative types won't create white dust, but they put out about half as much humidity.
    I now have humidifiers hanging from plant hangers attached to the ceiling outside the tent, and blowing into the tent, so that they don't take up floor space inside the tent, or blow humid air onto the plants.
    But it took a right angle tubular attachment from Lowes, and a bit of DIY to do it.
    • Like Like x 1
  11. That's awesome, I'd love to see a pic. Also may I ask, how much calmag do you add to your RO water? Ever since I got this RO system I've been having calmag deficiency problems...

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  12. After much costly trial and error involving about a dozen different brand humidifiers, I settled on a VAVA top fill ultrasonic.
    The first picture show the VAVA lid with the mist aiming device removed and replaced with right angle tube from Lowes.
    The second picture shows the humidifier mounted on a plant hanger attached to the ceiling.
    Here are links to some of the equipment:

    • Like Like x 1
  13. Wow that's frickin awesome dude!!! Kudos. I think I'm gonna design something like this based on what you've done. Good work.

  14. Looks like my post got hijacked. Oh well...:confused_2:
  15. Sorry bro, have you had any luck getting your temps down since the night you posted?

  16. No worries man, it happens. I'll be posting updates once I get my new fan installed
  17. I was having similar issues once upon a time. I just leave one of the side doors open. Also I have a fan blowing on the ballast for my HLG lights. Brought temps down.

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