Burning Leaves

Now right now i have a room set up in a basement running my first indoor grow. Now this room is about 5ft x 10ft. Im pretty sure my problem is my ph level but also right now i have no exhaust running out of the room. Now how big of a problem could this be. How important is it for me to have new air coming in the room?

It's important to have air exchange going in a grow room. You'll bring in more CO2 and maintain temperatures and resist mold and mildew development. If you don't bring in fresh air, eventually mildew will develop if nothing else does. why is pH a problem? what do they look like?