Venting /Temp/Humidity Question With HPS

I was planning a DIY aero/sog grow.

The area I have to work with is 4' high. The grow areas I have are 4x4x4' cubes with reflective mylar.

I am planning on cool tubing 400W HPS in each grow cube.

My question is about how I run the venting.

Will it be OK to use the cool tube duct to draw air out of the chamber (through the light), and then through a charcoal cannister, then out the house?

Basically doing all the venting with one tube.

Also, do you think I can keep the temps down to under 75 if the room is 65?



Humidity: Will one of those small dehumidifiers be able to keep the chamber dry, or will incoming air overwhelm the dehumidifier?

The way I am doing it is, Carbon filter -- Fan -- Cool tube -- Exhaust
You don't want your fan after your light because then your cooling your fan with hot air, and the decision to suck through your filter or blow is up to you I decided to suck for my design.
If your ambient air temp is 65 I don't see you having a problem keeping your temps in check as long as you have the air being moved quickly enough
Sorry I don't have any experience with your other questions, good luck!

sounds plausible to me only because your only using 2 400s. any more and i would suggest running separate exhaust and cooling. ideally you would want it to run filter>fan>light>out but it sounds like you have a bit of a space issue. so run it fan>light>filter

i have a 600w hps and my temp is never higher than 78. i use 2 fans. one is hooked w a carbon filter and the other is a big fan in the middle of the room to move around large amounts of air. the a/c in my house is at 74 and it seems to make a nice balance in that room.

how would you guys vent a small 45cmx45cmx60cm 250w MH clone box. im hitting temps of around 90+ with my door open , with doors closed it rises. ive made my ballast remote but this had no real effect, which was annoying as hell.