I've seen 1 light that I believe had it's lens broken by the expansive force of ice over the winter (or maybe some truant pulled back the cover over the winter and hit the lens with a hammer

),
Since I ~ know it can happen, let me tell you 2 ways to protect the light.
1) Unscrew the light from the niche and let it sink to the bottom of the pool
2) Unscrew the light and bring it up on the deck and put a bucket over it (if you lay it lens down, put a rag or similar on the deck

)
I hope you'll stop by from time to time over the winter, it's a little slow here

and we'd love to have some questions and pools to discuss
Have a great winter!