rfm2nd,
The lack of responses to your question regarding calcium meters has little if anything to do with reef tank hobbyist's desire or demand for such a device. It just shows a lack of response to your question - nothing more.
There are many manufacturer's that currently have "Specific Ion" analyzers available, and in use around the world. Mostly for industrial process applications and environmental water quality laboratories. Measuring the Ca+2 ion concentrations in a reef tank is possible using these analyzers, but as Ironreef said - they are very expensive.
Most reef tank enthusiasts will not spend that kind of money, nor will your aquarium products manufacturers market such devices - the price is too high for the average reefer with a 55 gallon reef tank in his family room.
The demand for such equipment is there - and if someone could manufacture and sell a meter like this for $150.00 bucks or so, I'm sure they would. Until then - test kits are by far the more economical approach for most of us.
You shouldn't give up your persuit of this issue though, especially if you have a true desire to do so. It would be in your best interest to develop such a device for sure - and you would be a "rich man"
Reefer's around the world would line up in droves, with their VISA cards out ready to purchase
Broomer
[ January 01, 2002: Message edited by: broomer5 ]