No announcement yet.

HPS Exhaust Light Leak

  • Filter
  • Time
  • Show
Clear All
new posts

    HPS Exhaust Light Leak

    Hey all,

    I'm getting ready for grow #2 and have some questions. My set up is: 600w HPS HID w/magnetic ballast in a 4x4x7, 2 AC infinity 6inch cloudline fans(one for light, one for 6inch filter).

    How do I stop light leaks from the light exhaust? How about light leaks from intake?
    I plan to use the GWE Stealth Window method, with some adjustments to fit my window.
    Click image for larger version

Name:	IMG_20210818_035014423~2.jpg
Views:	185
Size:	723.9 KB
ID:	531581

    The window faces my neighbor's yard. Could I add a backdraft vent too?

    Would passive or active intake better suit my set up? I'm planning on doing 2 MSNL Sour D autos

    Much love, thanks in advance

    If you add a couple of 90° elbows it would diminish the light quite a bit. A backdraft dampener would help but only when the fan is off. Whenever you turn a corner with your vent it drops the cfm significantly. A added fan on the intake might help with that, it can't hurt.
    DIY 4x12 Farmacy box w/2 4x4x6 grow areas
    TrolMaster HydroX runs the whole show
    Dual tank Co2 injection w/ rain tubing
    10000 btu thru the wall A/C / 5000 btu heater
    50 pint dehumidifier/ cool mist humidifier
    8" intake fan w/ hepa filter / 8" exhaust fan
    2 Timber Fatty-vs COB 950 watt draw fixtures
    w/ added 4 2ft T5 Pure UV bulbs on each fix.
    2 DIY Hybrid DWC 5 gal bubble bucket systems w/ 55 gal reservoirs w/ PH dosers
    2"x4"cyl.stones in buckets, 8"disk in reservoirs
    GH Flora series (entire line) + Orca
    Photo Grow #2 = Blue Dream and Black Widow


    • grouchyoldman
      grouchyoldman commented
      Editing a comment
      Smoklahoma, Good info, thanks.

      Any idea how much an 8" backdraft flapper valve reduces CFM? Same question, a 90 degree ell? I'm pushing output from an Infinity T8 and I want to optimize the max volume.

    • Smoklahoma
      Smoklahoma commented
      Editing a comment
      Not sure? I've got 8 inch backdraft dampeners on intake and exhaust to try and keep the co2 in the room. 8" Can Fan HO exhaust set to about 50% with 1 90°, 8" AC infinity s8 intake set to about 65% ( I forgot how many lights were lit ) with 1 8" 90°, 1 8 round into 4x16 rectangle 90°, 4 4" PVC 90° elbows. That makes the visquen lift off the wall slightly. Not sure about the math part?

    At any joining point of ridged to ridged or ridged to to flexible ducting the use of foil tape will help keep light out its also advisable to use the tape to seal all the swivel joints on the elbows. I also painted the inside of my ridged duct work black to reduce lights reflection. Make sure to use use insulated flexible ducting the material of just flexible duct will let some light through, the insulation covering is what keeps light out.


      Here's my version of that build. With this many turns and the venting off the hood I am not worried about light leak. Also with the exhaust through the blower it will block the light. Exit through the top of the tent to get the right light prevention. I still get a massive draw and find no discernable loss.

      Click image for larger version  Name:	Tent.jpg Views:	0 Size:	671.8 KB ID:	531665


      Check out our new growing community forum! (still in beta)

      Subscribe to Weekly Newsletter!