Water Hardness

[GouramiFanatic]

When I research different fish to find out which ones I want I pay close attention to their preferred water conditions. I always avoid fish who don't fit in the Ph range that I'm currently at, but I'm not to sure how important it is to try to meet their water hardness needs. What effects on the fish does it have if the water is to hard or to soft?

 

[Devilishturtles]

Water hardness and pH usually go together. The harder the water, the higher the pH, usually (not always though). The lower the hardness, the lower the pH. Harder water has a better buffering capacity than softer water. Generally, if you are trying to keep fish that prefer softer water, and thus a a lower pH, than water hardness is important. Fish that can withstand a wide range of pH, can also generally withstand a wide range of hardness.

Hardness also effects fish in osmoregulation. If you know anything about osmosis, water moving from a higher concentration to a lower concentration, than you should understand how this works. Generally, you want to try and match the hardness of the fish, so that the fish doesn't have to work so hard to find that happy balance of nutrients.