The reason you didn't get any replies is that there are very few people on this board who use a calcium reactor. They are very expensive. You wouldn't get all the excitement over a $3 bag of sand if you weren't so worried about money.
The best Calcium reactor on the market, in my opinion, is the Marine Technical concepts. It is pricey, about $700 NOT INCLUDING the C02 system. It has two cylinders, the smaller one is there to help keep any residual C02 from getting into the tank. The Knop is probably the next most popular, and it's less than half the cost of the MTC. There are new models coming out all the time. Korallin (sp?) is also pretty popular.
Sonny