If you look at the paper by Sears & Colin which gives the recipe for PMDD you will notice that they say to refridgerate it if you don't put the Hydrochloric acid in it (which would prevent things from growing in it). This is the same idea behind refridgerating your Flourish mix. Cheers, Mark pearlsco at u_washington.edu The more people I meet, the more I like my plants.