don't fix it if it ain't broken?

[kolosy]

my calcium declines over time, my alk stays constant. should i dose with a ca chloride (liquid calcium), do kalk or kent's part a and b?

the later two seem to address the whole equation, where mine seems to stay even...

 

[pledosophy]

If your just low on Calcium, just dose calcium.

Are you using a pH buffer?

 

[IslandCrow]

That really doesn't make sense that you're only depleting calcium. I don't think there's anything in the tank that uses just calcium. What are you using to test your water? What (if anything) are you currently adding to your tank for supplements? This may be a question for the chemistry forum, because it just doesn't sound right to me.

 

[Randy Holmes-Farley]

How much of a calcium drop are we talking about?

If it is large, calcium probably drops for you due to water changes with a low calcium mix, unless alkalinity is being boosted by other additions (such as tap water, pH boosting agents, etc).

 

[reefworm]

these chemicals affect each other, so a balanced approach is needed. I've had success with dripping kalk and vinegar [see first link] and using the 2-part Bionic to "bump" the levels when needed. Your Kent's A and B should do the same job just fine.
http://www.reefscapes.net/articles/breefcase/kalkwasser.html

these links explain the relationship of calcium, alkalinity and magnesium. the second gets pretty involved, but all good reading for understanding why things work, or don't.

http://www.reefkeeping.com/issues/2004-05/rhf/index.php
http://www.advancedaquarist.com/issues/nov2002/chem.htm

 

[kzickovich]

What type of salt mix do you use if it's intant ocean that stuff runs low in calcium to begin with

http://www.reefcentral.com/forums/showthread.php?s=&threadid=1287118

I do a mix of instant ocean and oceanic salt I haven't dosed in a long time