Hot spots occur when the light being reflected is unbalanced. This is often caused by the hood being too close to your plants. Some hood types will always create hot spots. I have played with light diffusers, and they do NOT work as well as you might think, at the very best they might decrease hot spots up to 70%. The best solution (other than raising your hood) is to have a fan blowing right over the hot spot to lower the temperature between the plant and the light. A more expensive way to fix a hot spot is to implement a light mover into your system. Light movers work great. The maximum benefit you can get out of a light mover (to keep the maximum light intensity) is a movement of 12”-24”. The ONLY folks that really need Co2 are the ones with a “Closed Room System”. This means you have NO outtake or intake fan. The systems are really only utilized where it is desert HOT. For most of us when we think of Co2, we are really trying to bump up our yield and veg times. But think about this, if your grow room is connected to your living space by the roof; you have a suffocating gas building up where you are. The one variable that keeps that gas out of your sleeping or hanging area is an outtake fan. What if a bearing fails in the fan, or the motor, or the breaker for some odd reason? I myself have become sick from Co2, just from working inside the room with the lights on. I have seen and read about adverse reactions when there is use of Co2 in warm indoor environments. If you have a room that tends to get warmer than 80 degrees, or if you anticipate your grow room being above 80 degrees when you cut your fans off (to allow the Co2 to build up), be careful! Also, what benefit do you get out of Co2? You will notice more vegetable matter than potency. So if you are growing botanicals think about that. Lastly, Co2 is ultimately a matter of style and desire. Keep in mind it becomes one more variable to monitor and can possibly harm you if not properly managed. If you feel the gain is worth the management, then give it a go!