Worried about my Temps

I have a 7' 3" x 7' 4" x 8' room outside in a shipping container. i have 3 inch thick insulation all aroudn the whole room. I have a 6" extraction fan the has a CFM on 435. When i have my fan on and my 1000w hps i can only get the room to about 55 degrees. My clean air is coming from outside and it can get cold betweeen 20 - 30 degrees. The temp is 75 without the fan on and just the light. I plan to purchase another 1000w hps but is this too big? I'm also cocrned my temps will be too low when the lights are off..

Try and keep temperature between 70-80 degrees. 55 is too cold. A drop of 15 degrees from day and night cycle is also too much.

Farenheit

How do i keep the temps up when the lights are off?

you might be able to reduce air flow"smaller ex fan. and put a small heater in by your in take. you can turn off your fan on lights out.

stumps is the man. Listen to him. Heater by the intake, fan off at lights out. +rep