Aquarium Water Temperature

For the vast majority of tropical fish, an aquarium water temperature of 76 to 78º Fahrenheit will be fine. Some species like cooler water and some prefer warmer water, but as a compromise, this range works well.

If you are having difficulty deciding what fish to buy, it wouldn't hurt to choose fish that prefer the same temperature range. Goldfish are not tropical fish and fare better at temperatures closer to 65º Fahrenheit.

It is very important that the water temperature be consistent. Rapid fluctuations in temperature, particularly down, may cause physical stress to fish that often leads to disease. The solution to maintaining the correct water temperature is an aquarium heater and thermostat.

Aquarium heaters are available in a variety of types, sizes, and prices. When it comes to aquarium heaters, trying to save money is not a good idea. The reliability of a heater is too crucial to risk buying an inexpensive one.

The weak link in any heater is the thermostat, which regulates the heater, turning it on and off to maintain the desired temperature. The quality of design, materials, and construction of the thermostat is one of the things that separate unreliable heaters from good ones. In cheap heaters, the thermostat often sticks -- either open or closed -- and this can be disastrous.

Aquarium Water pH Levels

Understanding aquarium water pH levels is important, not only to have an idea of what it is but also to compare later with the tank water to judge how things are functioning in the tank. 

A simple aquarium water test kit will provide a reasonably accurate reading of the pH. The pH scale runs from 0 to 14, and for monitoring aquarium water, you need to work in increments of tenths.  

A pH value of 7 is the midpoint, which means the water is neutral. As the pH values go down from this midpoint, the water is increasingly acidic; as the value goes up from the midpoint, the water is increasingly alkaline.

A change of one whole number (i.e., 7.5 to 6.5) actually represents a change in acidity or alkalinity of 100 times. Many aquarium fish that originate from South America prefer softer, more acidic water, whereas fish from East Africa do best in hard, alkaline water. These are just two examples.

 

Unless you intend to breed a species that is very particular about water chemistry, you will find that the stability of the pH in an aquarium is far more important than the exact value. Large, rapid changes in pH are often fatal to fish. Any change greater than 0.2 in a 24-hour period will cause physical stress for most fish.