Your fish tank’s water hardness may be one of the least important elements of the water chemistry puzzle by itself. Does that mean you can just forget about it? Not really. Let’s learn a little about aquarium water hardness and why you must keep it under control.
What Does It Hurt?
Your aquarium’s water hardness plays a very important roll. The harder your tank’s water, the more calcium carbonate (CaCO3) is in the water. More calcium carbonate (CaCO3) in your tank’s water gives your water a higher buffering capacity. Your tank’s buffering capacity makes it more or less resistant to pH changes. This is VERY important to your fish. You see, while the hard or soft water itself may not be preferable to some fish, it’s usually livable. pH on the other hand is a different story. If your aquarium’s pH is too high or low it can be very stressful for your fish. The two are really interrelated. The most important thing to take away is this. Hard water is more resistant to pH changes and pH changes are bad.
Aquarium Water Hardness Basics
Here are some basic terms that are related to water hardness. You’ll want to get yourself a test kit. Your kit should have these but this will get you familiar with the measurements and terms.
- DH – Degrees of Hardness
- KH – Carbonate Hardness
- GH – General hardness
- Very Soft 0-4 dH – 0-70 ppm
- Soft 4-8 dH – 70-140 ppm
- Medium 8-12 dH – 140-210ppm
- Hard 12-20 dH – 210-350 ppm
- Very Hard 20+ dH – 350+ppm
What’s the Ideal Water Hardness Level?
It depends on the fish species. Read up on your specific species. Remember to choose fish that prefer similar environment. Also, don’t forget the relationship between buffering capacity and pH. The harder your tank’s water, the more stable your tank’s pH will be. If you tank’s KH gets into the “Very Soft” area you should be paying special attention to you aquarium’s pH.
How Do I Raise My Tank’s Water Hardness?
- Filter your tanks water through crushed coral.
- Add baking soda (NaHCO3) to your fish tanks water – 1 Teaspoon per 26 gallons (100 liters) – This will raise your tanks KH around 2 dH.
- Add calcium carbonate to your tanks water – 1 Teaspoon per 26 gallons (100 liters) – This will raise your tanks KH and GH 2-4 dH.
What If I Want To Lower It?
- Boiling your tanks water will reduce its hardness although it’s not very practical.
- Filtering your fish tanks water through peat moss .
- Water softening pillows can be found at your fish retailer that uses an ion exchange method to soften your tanks water.