First you need an air-cooled hood. You can get a cool tube from eBay for about 125.00 usd or less if youâ??re lucky. With the cool tube you can get the light to with in 12" of your plants. 3 feet away is way to far you are loosing almost all the lumens and the plant is not getting the light it needs.

I use a remote temperature probe to monitor the heat at the top of my plants under the lights. Keep it below 85 at all times. Use a fan to move air around the room. IF you have a sealed room then you need to exchange the air a few times a day.