Update:
My seedlings are loving the clonebox. Shooting up nicely!
My seedlings are loving the clonebox. Shooting up nicely!

I suspect exposure to too much light for too long could damage them they are not adapted to light exposure. That being said, I previously had a clear tote for a clone res and never had problems with it. In fact, I had seedling grow 8" roots in three days in it! I suspect the plastic blocks the UV that would be damaging. The biggest problem with light getting in is the possibility of root rot.by changing the res every 2-3 days I've never had that problem. Thats also why i bought the smaller res, easier to handle at res change time. The other was rather heavy when full of water, was too easy to make a mess...Pop do you know why they say not to let light get to the roots? I pull the cups in my unit to test the water and fill res. I'm not sure I'd notice but I've never seen any probs exposing the roots to light.