I've never heard of a "treatment" that could be applied to existing glass to make it less green. However, on this forum I've read about Starfire glass which is significantly less green. Try searching this forum for "starfire" using the search box at the bottom of the forum.

Starphire glass is made by reducing the iron content in regular glass. this removes the green tint which is bothersome in thicker glass that is used in shower panels. the thicker the glass, the green tint is more pronounced. This is usually unacceptable to designers and clients that pay a lot of money for tile work.

Bright white tiles will retain their whiteness when viewed through the low-iron glass.

I highly recommend using this for your shower.

That was SOOOO helpful!! Thank you both so much!

We have a half inch Starfire glass panel that looks completely clear with no green tint. We also have a diamond fusion coating to resist spotting. One of my great fears was having to squeegee after each use since I am inherently neatness challenged. No need, a cleaning every 2 weeks suffices. Great stuff.

Thanks for the extra info, zinnah. I am also (and my significant other more so) neatness challenged and balk at the thought of enforcing squeegeeing after every shower.