Tin foil isn't recommended. Some say it makes hot spots on your plant and will burn them....especially if you're using HPS.

Your pots are prob too small. I would move up to a 3 or 5 gal pot. The roots will grow a great deal in the first few weeks of 12/12 still and you don't want to be transplanting once flowering has begun.

Don't have the fan blowing right on or through your plants. It will make condensation on your plants and could rot them.

Have the fan directed at your light and blowing across the canopy of your plants to get rid of the heat between the light and plants.