AAAARRGGHH!!! I DONT UNDERSTAND!

[faithlessxxx]

Thanks for taking the time.
Heres a quick diagram of what I have:

[dusto2k3]

no problem, frustrating huh. What are the ambient temps around the grow room. ie, what is the temp of the air coming into the room via the 4" intake? You might want to crank that fan up as high as it can. I see the tempo in my room go up 5 deg. F when my light comes on.

[invision]

if there are two 90degree elbows in your ducting that is why you cant exhaust as good as you want, move your light up the top and raise your plants to the light so you can get rid of the bows in the ducting.

[dusto2k3]

yeah, that would help invision, but realistically, lowering the plants every couple of days?.....a lot of work, and supplies...or do you have an easy method?

[faithlessxxx]

Hmmm, but that would move them away from the cold air inlet.
Might be worth a try though.
The ambient temps, air coming in, is around 21-22c.

[dusto2k3]

maybe crank up your exhaust. seems like you have you ducks in a row. I do have my fan blowing on my light. I dont know what works better, i never tried the other way. I run the vent for my light completley separate then the vent for the grow room. Two fans going out, and 1 coming in.

[dusto2k3]

you might try cranking up your exhaust. I run me vent for the light completley separate from the vent for the grow room. Two exhaust fans, one intake, and passives as well.

[faithlessxxx]

Hmmm. Looks like Im banging another hole in my rented apartment...

[dusto2k3]

this is my set up. it works well. I still see the temps risae when the lights are on

[dusto2k3]

ahh, that sucks. How do you have a lease there?