Help with Alkalinity

[no_Wedge]

My tanks alkalinity is dkh 7 (a bit low for my liking) and calcium is 420ppm. However, freshly made waters alkalinity is 12 and i don't know why it's so low in the tank. any help would be appreciated, oh and ph is 8.2-8.4

[no_Wedge]

did about a 15% water change and alkalinity went up to 8dkh, should I just continue doing small water changes every other day?

[RA]

Read this it should help.

http://web.archive.org/web/20021127040526/http://www.advancedaquarist.com/issues/nov2002/chem.htm