best way to light proof my box?

axiom420

New Member
i am building a wood grow box. i was wondering what are some ways to make sure light dosent come in my passive intake? i will probably have 2 4" holes. and i wont have any room to run ducting outside of my box from the bottom.
 

ruffrider

Active Member
90 degree angle on what?
90 degree Duct Elbow even better paint it black on the inside, Also you could get either a vent cover or return air grille put it over your hole and double up some of those black furnace filters works like a charm.
 

axiom420

New Member
90 degree Duct Elbow even better paint it black on the inside, Also you could get either a vent cover or return air grille put it over your hole and double up some of those black furnace filters works like a charm.
perfect thanks
 

axiom420

New Member
one other question..... i building from wood, if i use cocking or something similar to seal all the corners. will that release toxins when heated? or is it safe for my babies?
 

Green Troll

Active Member
Use plastic pipe bends. Remember your intake hole doesn't need to be any bigger than your exhaust. See https://www.rollitup.org/grow-room-design-setup/672557-passive-air-intake-question.html for details explaining how to work that out. Use a pipe bend and just point it down towards the floor. Rubber cement it into the hole and you are sorted. Use black pipes if you can as they are the least reflective. Bit of a non-restrictive filter over the pipes (panty hose and rubber bands) to keep out bugs and dust and you are done.

Now for the rest of light proofing. Turn your light on inside the box, and close the door. Switch the light off in the room and see where the leaks are. Rubber cement or Gorilla (not duct) tape over the parts of the box where its permanently fixed. As for the door, hinge it so there is a 3mm gap between the door and the rest of the box, and use this stuff. http://www.amazon.com/M-D-Building-Products-2253-Density/dp/B00005202X/ref=sr_1_1?ie=UTF8&qid=1371643986&sr=8-1&keywords=foam+sealing+tape

This acts kinda like the seal on your fridge door. Stick that around the framework of your box where it comes in contact, and when you close the door, it should squish into it and form a seal. Its black, and its waterproof, which means its light proof too. The door will need to have a catch or something to hold it in place on the opening end because the foam tape will be under pressure and it will try and force the door open. A Velcro strap is good for this! Saves you having to measure a little metal gate latch to close just right, pain in the ass.

If you want double doors, like a wardrobe or something (actually using a wardrobe saves you a lot of cutting and measuring!) you will need a small overlap piece of timber to cover over the top, front and bottom of the gap down the middle. That is a pain in the ass. Easier way is to have a single strut of timber down inside the box where the 2 doors meet. Then you can run your foam tape down it. Velcro straps on the top and bottom of each door to pull tight into the foam tape.
 

Green Troll

Active Member
Apparently i was wrong about the intake size needing to be the same as the exhaust. Apparently is supposed to be 3-4x the size. So ignore that bit.
 

rwbrock

Active Member
You won't need 3-4 times bigger if you making 2 vents. You are in a wood box as well so not like its a tent sucking in from negative pressure. I did a 6" passive intake and have a 4" ducted out. I actually rigged a small 5" fan to from cvs to some ducting help with the negative pressure and have to bent so light does not come in.
 

Green Troll

Active Member
You won't need 3-4 times bigger if you making 2 vents. You are in a wood box as well so not like its a tent sucking in from negative pressure. I did a 6" passive intake and have a 4" ducted out. I actually rigged a small 5" fan to from cvs to some ducting help with the negative pressure and have to bent so light does not come in.
Well that's what i thought! But there is a lot of documentation to say i'm wrong. Something about vortexing or some shit. God knows. But when 4-5 different sources say i'm wrong, i guess i am wrong :) I guess an intake fan would change things a lot though. Too much aerodynamic math for me though xD
 
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