Yes, I use a calibrated 200 gram lab balance to measure chemicals. I store them in a room with a dehumidifier in sealed jars. Since I use RO/DI water, it's a bigger concern for me since I'm adding these salts every week to completely reconstitute the RO/DI water. I verify levels after each water change using test kits. Potassium, GH, and KH. Test kits can be inaccurate, however, the bigger concern is keeping the water chemistry stable from the week to week 40% water changes. So it's getting the same results each week using the same test kit that's important to me. It's quite often in fact that I'll be off in my targeted dosing, so I'll dose more or less the next week to get back on target. If I never tested, my levels could go way off after a couple of months. I am honestly still amazed that using lab grade chemicals generates the amount of controversy that it does! [Laughing] Dosing, purity, testing, etc. seems to be pretty common in the marine/reef side of the hobby. [Wink] On a side note, I didn't know responding via e-mail would publish the response here under my real name. That's a pretty serious privacy issue if you ask me. If those posts could someone be switched to my screen name by a mod/admin, I'd appreciate it. [Wink] -------------------- m2f -------------------- Read this topic online here: http://forum.aquatic-gardeners.org/viewtopic.php?p=1514#1514 -------------------- m2f -------------------- _______________________________________________ AGA-Member mailing list AGA-Member@thekrib.com http://lists.thekrib.com/mailman/listinfo/aga-member