Well- I guess I might be the sole voice of dissent here. I've had FAR greater success using (can't speak about amber since I've never used them) but BROWN glass bottles than plastic. I find if you use a good quality chemistry type brown glass bottle and keep it filled to the brim, then your chems can last up to 3x longer... perhaps it's just the plastic I was using was poor grade or something - I don't know. But that's been my experience.