In my 45 breeder, dosing KW worked well until my corals grew to the point where KW just could not keep up with the demand. I would suggest starting with KW only, and watching it for a while. If you have really good coral growth, eventually you might have to supplement. I built a calcium reactor, and have it adjusted pretty low, while continuing to dose KW, although I'm using a weaker solution.

Here's my KW dosing set up: I use a 5 gallon glass jug with a 2 holed stopper mounted on a shelf next to the stand, just above sump level. In one of these holes is a long pyrex pipe that goes almost to the bottom, in the other hole is a short pyrex pipe. The short pipe gets connected to a vinyl tubing that's connected to a hard plastic cylinder suspended vertically at sump water level. The long pyrex pipe is connected to a vinyl hose that goes into the sump, under water level. This is the KW output, and the other is a siphon/air inlet. Once you start a siphon, KW flows into the sump until the water level reaches the bottom of the cylinder, cutting off air to the 5 gallon jug. This works great as an auto-top off, with KW as all top-off water.

If you're using KW only as a calcium/carbonate source, you might try spiking the KW with vinegar, up to about 30ml/gallon. This does two things; increases the solubility of calcium hydroxide in water, and lowers the ph so you can safely dose more KW.

I have to say, though, that since I got my calcium reactor up and running, my levels are more stable with basically no work. My 45 has a very high calcium demand; it's really crowded with sps colonies that were once frags.

Matt