Interesting data. Were these all taken at the same time of day? Any changes in husbandry or stocking coincide with any of the more significant swings (e.g. this March). Anyway, clearly you have a good reason to look into this option and I didn't mean to be overly critical... I do worry, however, that it could cause a bit of a rebound effect if one tries to "over manage" these parameters. Of course, I would love to know what caused the spike in my tank a while back!