By David A. Lass
Before you start an aquarium, and also if you encounter any problems with an established tank, the first thing to find out are the values for:
• pH
• Hardness
• Alkalinity
• Chlorine/chloramines
You can take a sample to your local fish store for testing, or buy simple test kits there and test the water yourself. There is, however, a basic principle to consider, which I call “Let the Fish Fit the Water.” Fish in general come from two types of water:
• Hard and alkaline – African cichlid fish, most livebearers, Central American cichlids
• Soft and acid – tetras, catfish, gouramis
You will have much better luck with your fish if you keep fish that prefer the water type you have, rather than trying to change the pH and hardness of your water for specific fish. If you do start playing around with your water chemistry, it is easiest to make soft/acid water into hard/alkaline than to go the other way. This is because to make soft/acid water hard/alkaline all you have to do is to add some minerals – primarily carbonates and salt. To make hard/alkaline water soft/acid you have to remove things from the water.
In simple terms – it is much easier to make your soft/acid water so that African cichlids will be happy in it than to make your hard/alkaline water good for cardinal tetras. If you do decide to mess around with your water it is really important to know the alkalinity, and to monitor the pH to make sure it stays where you want it.
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