increase or decrease the alk

[nandan]

hi i have a reef aquarium in which i add kalk via gravity dosing and also add ph buffer, will this help me keep the alkalinity stable. or should i use somthing else

[Randy Holmes-Farley]

For many tanks, limewater (kalk) alone is fine. It is all that I add for calcium and alkalinity. If you have a lot of SPS corals and thus have a high demand for both calcium and alkalinity, then you may need to use a different method along with or instead of limewater, such as a two part system or a CaCO3/CO2 reactor.

But I would not normally add pH buffers alone. They do not do much for pH, and they boost alkalinity relative to calcium.

This should help:

The “How To” Guide to Reef Aquarium Chemistry for Beginners, Part 2: What Chemicals Must be Supplemented
http://reefkeeping.com/issues/2007-04/rhf/index.php

How to Select a Calcium and Alkalinity Supplementation Scheme
http://www.advancedaquarist.com/issues/feb2003/chem.htm