Do supplements expire.

[tim the toolman]

I bought a second hand system from a guy who hadn't had it running in over a year. I am not setting up that system but I'm wondering if the supplements expire. I got a whole box of misc. supplements including Tailored Aquatics calcium, dkh raiser, phosphate destroyer and many of the like. I don't see any expiry dates on them but I just wanna ask to be sure.