Hydrated Lime
 

For those on a budget and want to save on Kalkwasser, you can pick up a 50 lb bag of calcium hydroxide for 12.00 at Port Kells Nursery in Langley.

Package is labelled Hydrated Lime Type "N" from texlime. the type "N" is what's important, don't buy type "S"

Of course it's probably not as pure as some of the commercial grade brands of Kakwasser, but then again maybe it is.