Originally Posted by AyalaCookiejar
Thanks - I'm not exactly sure what kH is and I don't have a test kit for it.
KH is alkaline buffering. Buffers resist a change in pH when a small amount of acid (or a small amount of base) is added.
Alkaline buffers attempt to maintain the pH within a basic (alkaline) range, which is the higher end of the pH scale. (On the pH scale, 0-7 is acidic. 7-14 is basic/alkaline.)
For example, blood is able to maintain a constant pH of 7.35 to 7.45 (just slightly alkaline) via the bicarbonate buffer system.
Likewise, you could create a buffer in a fish tank by adding a small amount of baking soda (sodium bicarbonate). The bicarbonate will counter any acid that is produced by the fish waste, and will keep the pH stable.
If a small amount of acid is added to plain water, the pH will drop quickly. Result: the fish is swimming in acid..... But if the small amount of acid is added to a buffer, the buffer will keep the pH from changing. Result: the fish is happy.
The ocean has a natural buffering system because of the presence of calcium carbonate. (Also found in sea shells and corals.) The carbonate acts as a buffer, keeping the ocean's pH stable.
When you test for KH, you're measuring the concentration of carbonates and bicarbonates. A higher number indicates you have more of these, which means you have better buffering capability. A lower number indicates that your pH can start to drop quickly, as wastes build up in the tank.