Question on exhaust/light

I'm currently in the process of rebuilding my grow room and have a question.

My exhaust is like this scrubber->1000w->fan->window

It's pretty much a straight shot to the window so I'm following this stealth window exhaust method: Video

http://video.google.com/videoplay?docid=-3522676950230105924#

Not sure since it's a straight shot that the speaker cloth will keep the light from my 1000w glowing out the window. I have been running my lights at night.

How do think I can keep my light from escaping out my exhaust?

Thx

if its a cooltube use black ducting and if you need to make a bend in the ducting otherwise block the end of with some kind of air filter which you an get at grow shops

It's a sun system blockbuster 8". I had a bend before hate to do that again as you loose a lot of efficiency with bends.

Black ducting will def help some. Will look into some type of filter.

Thx

Black flex duct so no internal reflections and some "S" curves so no direct line of sight.

just put a couple of 90 degreee turns in your ducting and it will get rid of a lot of the light