ya i drilled 1/2 inch holes all in the bottom and even a few around the outside bottom edge then put enough rock in first up to and just above the holes so the medium wont clog the holes later.......so nothing wrong with the white of the buckets though? some people say to paint them black????
Yeah, they don't like the nute solution being exposed to the lights, supposedly that can cause some nasty crap to grow in the solution. Mine are black but I'm not sure how serious a problem using white would cause.
Algae can grow in them if light is getting through, it doesn't take much light for algae to get a foothold . Just duct tape the outside of the bucket, easy nuff.