Carbonate Hardness (KH) levels need to be tested on a regular basis because
they fluctuate over time and can negatively impact the pH balance of the
aquarium water. Low Carbonate Hardness will result in poor plant growth. Testing
for General Hardness (GH) should be done to determine if the levels of Calcium
(Ca) and Magnesium (Mg) are optimal for specific species of fish.