Kalkwasser??? Kalkreactor??

[EWC88]

Hey guys what are these things used for? and should I get one for my tanks??

[marduc]

this should help some (http://www.reefkeeping.com/issues/2005-01/rhf/index.php#5) and this (http://www.advancedaquarist.com/issues/feb2003/chem.htm)