lol. Excellent points and I'm glad Roger spelled them out. I'm laughing at myself because I hadn't really thought about dosing accuracy as the key issue with the refinement of fertilizers. I was actually focused on the idea of introducing unwanted contaminants to the aquarium. I suppose that, as much as the accuracy/inaccuracy matters, the precisely correct dose - if there really were such a thing -- would depend on a wide variety of factors including species, the environmental conditions. I think successful gardeners aim for targets as general guidelines but use the results in plant response as the key indicator of "correct" dosing. I doubt that many successful gardeners focus on specific numbers any more than that. I guess I'm uncertain that the notion of "10% incorrect dose" even applies to planted aquaria. -- it would be such an artificial and arbitrary thing. Otoh, "10% off target" is a simple arithmetic measure, albeit not very meaningful for aquatic gardening purposes for the reasons that Roger so nicely points out. sh -------- Scott H. -------------------- m2f -------------------- Read this topic online here: http://forum.aquatic-gardeners.org/viewtopic.php?p=1511#1511 -------------------- m2f -------------------- _______________________________________________ AGA-Member mailing list AGA-Member@thekrib.com http://lists.thekrib.com/mailman/listinfo/aga-member