Jason, My calcium levels went up a bit when I added mine to the tank. From around 400ppm to around 450ppm now. I'm not too sure about the whole theroy behind them not rasing calcium. <img src="graemlins//yeahright.gif" border="0" alt="[yeahright]" />
Most tanks can be maintained with kalk. The larger tanks with more stonies and coraline that are really dependent for growth off the calcium are the ones that have a hard time raising the level.