Keep in mind that the temps will drop a little when you actually introduce the plants into the room with fresh cold water. You can also try putting the ballast/s outside of the grow box because they generate a lot of heat as well. Up to 3-5 degrees even. If you still cant get below say.... 90 Degrees. Try introducing Co2 into the enviornment. Good ventillation and Co2 will help overcome and offset high temps.

Happy Growing....