Say you have two lights facing one side of a plant and place a large mirror on the other - will the light reflecting off the mirror act as another light or is that all just a load of bull?
Not according to the inverse square law. Plus mirrors tend to absorb most of the useful light to plants. Its great at reflecting the wave lengths of light our eyes see though. Bottom line is mirrors are not a good thing in the grow room...so a load of bull...
That depends.. if you're using it to redirect light to lower foliage.. you will be spending 100s to 1000s of dollars in real mirrors. A 30 dollar mirror in a store will absorb more light than it reflects for the most part (see: all vanity mirrors) You'd need a Bragg / dielectric mirror to get any real reflective power out of it and make it worth while.
Say you have two lights facing one side of a plant and place a large mirror on the other - will the light reflecting off the mirror act as another light or is that all just a load of bull?