I'm building my first grow box while waiting on my seeds to come in, and I am using a big ass mirror directly opposite the bulbs at a 45 degree angle so all the extra stray light gets reflected back into the box. I thought this was a great idea. Why do you say mirrors are inefficient? White paint won't reflect as much light as a mirror, its practically 100% reflection. Hell aluminum foil is suggested often, and you can make our your reflection in foil, but not nearly as good as a mirror. So, I just want for you or someone to explain why/if I should take out the mirror. Seems like the mirror would be the best, not the worst.
The glass on the mirrors absorbs light and only reflects around 30% or something close to that. If you get good quality mylar, your getting 98% reflicivity
Wow, i never knew that. Thats freakin crazy. Thanks for the info, I checked out mylar and you can get a 4x10 foot sheet of it for under 20 bucks shipped. (on ebay)
you might be able to get it for a lower price at a store. I found a website that can help you find one http://forum.grasscity.com/absolute-beginners/467307-growshop-locator-reviews.html
Home Depot sells Reflectix in a 2' and 4' roll for $20-42. Its 95% reflective, made over bubble wrap for durability and noise reduction.
Household mirrors are only about 65-80% reflective. A flat bright white painted surface reflects more, about 85%. Mylar even more, 90+%. And by mylar I mean horticulture grade not space blankets...