cplev,
oh, and don't forget about kalk danger ( overdosing) which a quick search will show you a few beautiful tanks, down the drain because of kalk overdose
that must be consider and a way to prevent it must be employed, that therefore adds to the price
such options are
SpectraPure LiterMeter III at $340
other dosing pumps, $ depend on where you get it
others have try cheap float switches and had pay the price,
as you can see a kalk setup can be costly, if you look around you can grab a nice setup for cheap
the other day locally there was a complete calc reactor setup 300,
anyway research and make sure you know all the corners, good luck,
sam