I have heard that if you shake the bottle and hear/feel "chunks"/globs of anything, then the nutes are bad.

Other than that, I don't know. If it were me though, I would use them as long as they were kept in a stable environment, good temps, not alot of light, and tightly sealed. If not, I would buy new.
norkali Reviewed by norkali on . Nutrient Expiration? Does anyone know what/if the shelf life is for base nutrients? They have been sitting for around a year. Wondering if they will still work correctly. Thanks. Rating: 5