Carbon Filter Pads Not Lightproof?

So I'm working on my newest stealth/micro project and I bought carbon filter pads [the kind that go in HEPA filters 'n such] thinking they would be completely lightproof, so I put two layers over my exhaust and a layer over both of my intakes. Not only were they not lightproof, but they hardly blocked any light at all! They only blocked about 25% of the light. So i added 2 more layers over the exhaust, and they still weren't lightproof! With 4 layers, they were only about 90% lightproof. In order to lightproof it, I added a piece of black cloth over the intakes and exhausts, and after a 18 hour temperature test, i was at 115+*! [my thermometer only goes to 115]

So my lightproofing job was restricting airflow so much, that my cab [which gets exhausted about 78 times in 60 seconds] was so incredibly hot, it burned my hand when i touched a metal piece that was on the cab.

My point being, did i just buy the wrong filters? I bought the Arm and Hammer brand [orange box]. I have seen elsewhere on this site, and others, carbon pads like mine being used to lightproof holes. If this is the case with all of these types of filters, then what else can I do to block light from my cab and block smell, without blocking airflow?

BUMP! and moving to "General Marijuana Growing"

none of the per-filter stuff is going to be light prof. as far as the heat issue the filter is some what restrictive which means you might need better fans to keep good air flow.