Robzilla
1) test your alk reading first and post the result. i suspect your alk is low which in turn has little buffering ability. test alk level in 24 hour periods to determine how much is used up in 24 hours.
2) read this
http://www.advancedaquarist.com/issu...l2004/chem.htm
to determine how much alk you need to raise it to achieve the level you want then how much to add per day thereafter
3) go to Superstore and buy a 2kg regular Arm&Hammer Baking soda for 5 bucks instead. much cheaper and works great to raise alk (hint hint don't buy the commercial Marine buffers)
4) follow up with your calcium and magnesium anytime after
hth
cwlee