Beta fish

A home aquarium provides hours of fun and relaxation — and health benefits too. Studies have shown that people who spend even ten minutes watching fish in tanks exhibit lower heart rates and blood pressure and an improved overall mood.

But what about the health and well-being of the fish in the tank? An aquarium should be a place your fish can feel comfortable and thrive. To create an appealing environment for your fish to live in, you’ll need to use the right kind of water.

In this guide, we’ll discuss what the best water for fish tanks is and how you can optimize the aquarium water for your fish’s well-being.

Aquarium Water Sources

When you’re providing water for the aquatic life in your aquarium, you can choose from a few different sources. For freshwater tanks, you can use the water source directly. For saltwater tanks, you will need to add a salt mix.

It’s important to note, though, that whatever water source you use will likely require some treatment to be safe and habitable for your fish. Always test and adjust your intended tank water before placing fish into it.

1. Municipal Tap Water

Perhaps the easiest way to provide your fish with a watery home is to turn on the tap. If your home’s water comes from a municipal water source, the water should be disinfected and free from most bacteria. However, the quality of tap water still varies widely by location. Some tap water may contain high levels of iron or magnesium. Other tap water may contain trace amounts of ammonia or asbestos that can wreak havoc on delicate fish.

Another issue with using municipal tap water for a fish tank is that it often contains chlorine, which many public water facilities use as a decontaminant. Chlorine is toxic to fish, and it also kills good and bad bacteria indiscriminately. Chlorinated aquarium water will kill the good bacteria that collect on your aquarium filter to break down the toxic ammonia and nitrite found in fish waste.

2. Well Water

If your home has well water, the water will not contain chlorine. But using well water for a fish tank can present several other issues. Unlike municipal water, well water is unregulated. Depending on where you live, well water could contain high concentrations of any number of different contaminants.

Agricultural runoff could introduce nitrates and coliform bacteria from fertilizer into your water — or runoff from an industrial plant could introduce volatile organic compounds (VOCs), like the chemicals found in herbicides, pesticides, paints and solvents. Well water can also vary in its pH and hardness, and it usually contains little oxygen, so it will require aeration before fish can safely live in it.

3. Bottled Water

Bottled water may seem like an ideal solution for your aquarium — it’s marketed as healthy for humans, so it must be good for fish, right?

Not exactly. Bottled water is typically either well water, filtered water or spring water. It may have gone through filters that remove some of its beneficial components, or it may have extra minerals that are unhealthy for fish. You would need to test and adjust it before using it in your tank. Some bottled water still contains high levels of chlorine that you will need to remove before using the water in your aquarium.

Bottled water is also significantly more expensive than tap water, so using bottled water in your aquarium will make the upkeep of your fish tank much costlier — plus, it’s impractical for large tanks because of the enormous number of bottles you would need.

4. Rainwater

If you don’t want to use tap water for your aquarium and don’t want to pay for bottled water at the store, one practical option might be to use rainwater. However, rainwater tends to have very low mineral content, and its pH can vary. So you would need to test and treat the rainwater before using it for your fish.

Rainwater can also easily become polluted with contaminants in the atmosphere. If pollution from nearby factories — or from the chemicals, smoke and exhaust of everyday urban life — is suspended in the air, raindrops can absorb that pollution as they fall. Rainwater that lands on the roof before collection can also pick up asbestos from the shingles.

Rainwater also presents the problems of availability and storage. If you live in an arid climate, rainwater may not always be readily available. You would also need a place to store after you’ve collected it.

5. Distilled Water

Distilled water is affordable, available at many stores and free from most contaminants. Producers create distilled water by boiling the water until it turns into steam. As the steam rises, it leaves impurities and contaminants behind. Producers can then collect the steam and bottle the distilled water for sale.

However, this process strips 99.9% of the valuable minerals from the water, including calcium, magnesium and sodium. If you use distilled water in your aquarium, you will need to remineralize it before adding it to the tank. Distilled water is also impractical for large tanks because of the tremendous supply you would need to purchase.

6. Reverse Osmosis (RO) Water

Reverse Osmosis water is water that has gone through a reverse osmosis filter.

Osmosis is the natural movement of water from areas of high particle concentration to areas of low particle concentration. Reverse Osmosis switches that process around, sending water through a fine membrane that traps particles on one side and allows clean water to flow through to the other. Reverse Osmosis filters are highly effective and make excellent choices for aquariums, though the water will require remineralization before you add it to the tank.

Reverse Osmosis is excellent at filtering contaminants, including minerals, chlorine and some larger bacteria. However, it’s ineffective against some bacteria.

7. Deionized (DI) Water

Deionized water is produced through the use of resins that trap electrically charged contaminants and exchange them for harmless charged particles like hydrogen ions. If you want to be sure your aquarium water is free from mineral and chemical contaminants, deionized water is a great choice. Deionization is ineffective against bacteria, but it does filter some contaminants that even reverse osmosis systems cannot catch.

If you use deionized water, you will still need to adjust it before adding it to your tank. The process of deionization tends to strip away essential minerals as well as harmful ones, so you will need to remineralize your water to make it optimal for your fish.

How to Condition Water for Your Aquarium

Whatever type of water you use for your aquarium, you’ll need to condition it to make it safe, clean and chemically balanced enough for your fish to thrive in. When you condition your aquarium water, consider these parameters:

  • pH: pH stands for power of hydrogen. pH measures the hydronium concentration of your water on a negative logarithmic scale. It determines whether the water in your tank will be acidic or alkaline. The pH shouldn’t be too high or low, and it should remain constant. Different fish species may prefer different pH levels — most freshwater fish do best at a pH between 6.5 and 8.5. Saltwater species may require a more alkaline pH, since the average pH of ocean water is about 8.1.
  • gH: gH is a measure of general hardness. It measures the concentration of calcium and magnesium ions in the water. Different gH levels are optimal for different species of freshwater fish. Water hardness is not generally an issue in saltwater aquariums.
  • kH: kH is a measure of the carbonates and bicarbonates in the water. Low levels of carbonates and bicarbonates decrease the water’s ability to buffer pH, and they lead to large pH swings that could harm the fish.

Your tank should also contain the right balance of good bacteria and minerals and be free from harmful substances.

To condition your tank water, you can test your water, figure out what it contains, and then add or remove substances until your water has reached the desired parameters. For example, you can buy a water conditioner that helps remove chlorine from the tank, or you can add baking soda to increase bicarbonate levels.

Adding Minerals Back to Your Water

If you plan to use distilled water, you may be wondering how to remineralize distilled water for your aquarium — and remember that remineralization is necessary for deionized and reverse osmosis water too.

To add minerals back into a freshwater tank, you can add a little bit of tap water to the mix. You can also buy a remineralizer at the store and add several drops of the remineralizing substance to the tank. With a saltwater tank, the salt mix you use generally adds minerals as well as salt.

Contact Long’s EcoWater to Ensure High-Quality Aquarium Water

To help provide your aquatic friends with an environment they’ll enjoy swimming in, work with Long’s EcoWater. We can assist you with testing your home’s water, and we have the filtration systems you need, including our Reverse Osmosis System, to keep your aquarium’s water clean and contaminant-free. We can also help you soften your home’s water for fish species that require minimal water hardness.

Contact us today to learn more!