Depends on the size and temps of your space. In most situations peple mount them outside, but either will work. They do get warm though, and will add a degree or two if they are in your cab
I don't have cooltubes and I keep everything in my closet. I have an 8" fan/duct running outside and drawing in air from the house. Temps can get up to 90f at the top but no higher then 85 at canopy level. The cool air get sucked from the bottom to the duct at the top then vents back down through my floor. It is working well but I think I'll have to put an ac in the room outside the closet during summer months.
I hope that all made sense. You can see pics of my closet in my Sweet Seeds grow log.
Grow under LED grow lights (Indoors)
There are growers that believe that the color spectrum being produced in certain modern LED grow lights can also add to the complexity of terpene content, similar to what happens with plants grown under the sun.
This may explain why some growers believe that indoor plants that are supplemented with LED grow lights have a better quality than ones grown just under a standard HPS light.
For example, I’ve noticed it’s becoming increasingly popular to supplement HPS grow lights with one or two LED panels during the flowering stage.
A few growers have made that claim that�*growing with�*a mix of both HPS and LED grow lights during the flowering stage can help imitate the complexity of terpenes found in buds grown under the sun. There have also been some informal tests by growers which indicate that using a mix of LEDs and HPS together also increases the trichome production and�*smell of cannabis buds.
Many growers believe that outdoor-grown or greenhouse-grown bud has a better taste and smell, and it's possible for indoor growers to capture some of that by using HPS�*and�*LED grow lights together in the budding phase of growth, especially during the last few weeks before harvest when terpene production is ramping up.