Tropicals & Tender Perennials: Fiberglass transmit enough light in g-house?, 0 by Wingnut

Wingnut wrote:
Does the milky-white corrugated fiberglass transmit enough light for plants to actively grow? I'm talking about the stuff that's on the roof of my greenhouse in the pic below (hope you can see it). Also, I'm talking about active growing in a heated house, not just overwintering plants. I always thought that stuff transmitted plenty of light for plants to grow, but today while calling around for prices, one person told me it wasn't enough, I'd need polycarbonate (that clear as glass stuff). Is this true? I don't think this person was a very reliable source, but you never know. Besides the two above, what about that frosted-looking corrugated stuff, looks like a frosted shower door and half the price of the clear polycarb ~ enough light for growing? Anybody know the % of light transmission for any of the above?