What kind of water is right for a fish tank?

What kind of water is right for a fish tank?

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Water quality is one of the most important conditions for the comfort of your fish. Let’s figure out how to choose the safest water from the whole variety of options.

Tap water

The simplest and most obvious is the use of tap water. It is available to the vast majority of aquarium owners and, if certain conditions are met, will suit many fish. However, you should be aware that the water from the city water supply is chlorinated, which means that a filter or dechlorinate should be used to remove chlorine from the water before pouring it into the tank. Otherwise, sediment hazardous to pets will form on the bottom and walls of the aquarium.

Deionized water

This water can be purchased at specialized stores. The deionization process helps to remove impurities and any particles found in the liquid, and also neutralizes the pH by eliminating various ions that may float in the water. Unfortunately, this type of water also poses a potential danger to fish. As all impurities are removed from the water, the chemical balance is disturbed. The liquid on its own can produce sudden and dramatic changes in pH, alkalinity, and hardness when exposed to any external factor – even aquarium equipment. It is important to know how to properly balance deionized water and add supplements for your fish or plants. Novice aquarists are advised to choose a different type of water for the tank, so as not to accidentally harm pets.

Softened water

For many experienced fish owners, softened water appears to be the best option. The main thing is to find out in advance whether a particular softener is safe (there are different manufacturers) for use in the aquarium tanks and carefully read the instructions for it.

Bottled water

Experts advise or popular advise using bottled water at a suitable temperature (here we mean drinking water without gas) only if the quality of the tap water is poor. The fact is that bottled water is often not tested in any way, so its parameters are unknown. In addition, bottled water often contains vitamins, flavors, preservatives, colors, or other additives. They can be fatal or not healthy to fish.

Fish tank with tap water
Fish Tank


If you settled on the most seemingly “natural” water, you should take into account a number of negative factors:

  • Air-condition;
  • Rainwater can carry contaminants from a source like pipes and pipelines, roofs, and other surfaces through which it flowed before entering your aquarium;
  • Your collection point and the risks of contamination in the collection device;
  • Rainwater rarely contains the necessary trace elements to maintain the health of fish and the correct chemical balance of the water.

Water from streams, rivers, lakes, etc

This water is not suitable for an aquarium for the following reasons:

  • May contain toxic contaminants;
  • Carries dangerous pathogens or bacteria for diseases for which your fish are poorly prepared;
  • It is a “home” for parasites that can cause an epidemic in the aquarium.

The choice of a novice aquarist

So what kind of water should you choose if they are all imperfect? Fish owners with little experience should still choose the easiest option – tap water. The main thing is to remember about dechlorination and change filters in time. Tap water usually has known and relatively stable parameters, so sudden fluctuations in pH are unlikely, which means your pets will be as comfortable as possible.

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