> It is more troublesome when people start recommending to others that they *should* use reagent grade chemicals or face a host of potential problems Well, to me, most people who project their practices on message boards, in magazine articles, etc., are basically saying "This is how I do it; I do it this way because otherwise I might have problems." So I don't really see it that way. I interpreted it as one idea, and it was troublesome to me that just about every administrator of the site jumped all over the guy(s) and called them trolls. > Constant and sometimes extreme changes are a hallmark of the freshwater environment That doesn't seem to make sense to me... you are saying if I have water chemistry flying all over the place, then my plants and fish will do better? I think in an artificial environment, stable water chemistry would be better. I haven't tested it, but I would be willing to bet that the tank with more stable conditions will do better than the tank with dynamic conditions. > those reason's aren't as important to fresh water tanks -- particularly when the "contaminants" in question are just chemicals that would occur naturally in the water anyway. But from what I have gathered from the posts, the other compounds in the salts and their levels are unknown. Someone said that agricultural K2SO4 is mined and sieved, with no additional testing or purification. In my mind, I think of what happened to all the contaminated bags of Eco Complete that were shipped due to mining contaminates. > the reagents used in test kits are not completely stable -- some of them are quite unstable. The results from a single test kit applied to a standard should drift over time as the reagents change. That does not follow my own results. For example, I have a pH monitor in my water at all times. I regularly calibrate it. I use the Red Sea kH test kit. When I hit the mark of 5 dKH, my pH monitor reads 7.38 - 7.42 (usually 7.40). It's been that way since I started using the test kit 6 months ago. It's almost out. So, these results seem to indicate no significant drift throughout the life of the kit. I would also think that more expensive kits (like Lamotte) would have serious marketing issues if they had a tendency to significantly drift throughout, say, a year. I also don't think that a kit would greatly drift from one week to the next, causing the hobbyist to mis-adjust a level by several degrees. -------------------- m2f -------------------- Read this topic online here: http://forum.aquatic-gardeners.org/viewtopic.php?p=1529#1529 -------------------- m2f -------------------- _______________________________________________ AGA-Member mailing list AGA-Member@thekrib.com http://lists.thekrib.com/mailman/listinfo/aga-member