I know a lot of tents use mylar or something reflective....but what about having mirrors along side the plants, maybe angled to bounce the projected light up under or to the lower branches? Thoughts? I use QB288's 26" above my plants if that matters. Thanks!
Good mirrors can reflect up to 90% or more of the light that hits them. A regular mirror will be more reflective than most tent reflective materials. A reason more people don't use them is that when dirty, they might be of negative assistance. I'd give it a try.
The problem with mirrors is the light has to pass through a pane of glass before being reflected by the silver backing and then through the glass once again before your plants recieve it. When the light passes through, a percentage of it is converted to heat. This is generally not what you want. Silver mylar basically reflects the same but doesn't have that glass in front of it so you don't lose that light and don't create that heat
Here's an excerpt from growweedeasy: Mirrors seem intuitively like a great choice, but in reality they are "just okay" (at best) for reflecting the light of indoor grow lights back at your plants. While mirrors are great at clearly reflecting your image back at you, they're not meant for reflecting light; especially light that is actually usable to your cannabis plants. Mirrors don’t reflect light from the grow lights in optimal patterns and tend to create light/heat spots. While better than a black wall, I strongly recommend not using mirrors for reflection in the cannabis grow area. Mirrors are "great at clearly reflecting your image..." partly because they reflect so well. Tent coatings are constructed to diffuse the reflected light without deteriorating, and use shiny, flexible materials like mylar. Mirrors will reflect light that has only slightly reduced intensity from the light that hit it, and in a straight line with little diffusion. Any "hot spot" created by reflected light will be slightly weaker than the hot spots already created by the regular lights. Certainly a mirror without a protective glass coating will reflect better than a mirror with coatings, but only by a few percent. Anytime you can make use of light that would otherwise hit a spot that doesn't promote growth, it's beneficial, and using a regular mirror to do this has to be better than nothing. I think growweedeasy is wrong on this. If you can use a regular mirror to make use of otherwise wasted light, you should do it. I'm not saying that you should replace existing coatings with mirrors.