Hart, I use a geo calcium reactor exclusively for my ca and kh additions. The star board is nice. However, it's a bit pricey. I salvaged my star board from a old butcher shop. They stunk like rotten meat when I got them. A friend had a plainer so we took the top 1/8 off and they turned out perfect. Otherwise I'd have spent 200.00 for star board. So check out your local shops for discarded starboard and save! The health department makes them replace the board after they have been scored to deeply fyi.