Calcium and Alkin

[whatcaneyedo]

Another option is to supplement a two part solution or 'The Balling Method'.

What do you plan on stocking your nano with? If you intend to keep many calcifying stony corals and clams you will likely find that doing water changes will not be sufficient (or you'll need to do very large and frequent water changes). But if you are setting up a soft coral nano you should be fine with water changes alone.

Heres an article that may help you decide: http://www.advancedaquarist.com/issues/feb2003/chem.htm