While Tom's answer might not be the, uhhh, most concise, it is certainly the most complete. Thanks Tom!!
Having spent a good many years as a health care practitioner, I have some understanding of compartmental dilution between intracelular, extracellular and interstitial components of human fluid and electrolyte balance, and such a phenomena in a captive reef system would certainly explain my observations. I just never thought of it in that context. Glad to know I'm not losing my marbles after all.
The bottom line is I'm doing 20% water changes weekly right now, so maybe I'll be OK in the long run. Or maybe I'll just go back to the drudgery of mixing up and dosing Kalk. Ugh!
Again, thanx....
Bert