how to block the light from light heat vent

I have a 1000 watt hps that is cooled by an inline 6" fan. The problem is the light is close to the exhaust window so a bunch of light shines onto my yard! How can I block the light without blocking too much air flow? I was thinking of stuffing some black foam into the inside of the window...any other ideas?

You can get central heat and air conditioner filters - NOT the type for the intake in the house - the one for the unit that contains the fan - typically in a garage or attic or on top of the house. They are thick filters, from 1" to about 2", they are a mesh type material. They come in sheets about 18" by 2', you can cut it to size. I have installed them in ducting before, just cut it a little big and wedge it in there. It is easy to breath but cuts down on light passed through. You could even double these up, put them in the ducting where the light shines in. It will stop the majority of the light and still let air pass through.

If light is shinning through your duct I would suggest wrapping it with metal, foil, tape. Kind of a pain but it stops the light from finding all the pin holes in the duct.

I stuffed some regular pink panther insulation in the window from home depot... cheap but not a complete fix. The problem is the light from the hps light is shining to the outiside and glowing my front yard through the exhaust duct. Any ideas on how to fix this problem?

make a loop in the ducting

or a light trap box

light trap box

make internal wall slightly longer
and spray paint every part of the inside "flat" black

That 5hit said:

make a loop in the ducting

or a light trap box

Click to expand...

+rep For loop in ducting

You can even cut the duct where you loop it and paint the inside flat black then reconnect and loop it for even better protection.

I did a loop in the duct right between the light and the wall... not much room there for the loop but it works, and cuts 90% of the light so far. i think I will paint the inside of the duct this weekend to get all the light away from the front lawn... thanks guys!

Speaking of pin holes in ducting, I suspect that is how some smell is leaking into my room. Does anyone know what kind of ducting won't have this pin hole problem?

Insulated ducting got rid of my issue with the pin holes. It is a larger outside diameter and harder to work with in small spaces tho