How To Reduce Water Hardness In An Aquarium

Last Updated on September 24, 2021 by admins

If you have an aquarium, you will want to know how to reduce water hardness in an aquarium. Water hardness will vary depending on where you will. It can cause all sorts of problems in your aquarium if not properly treated.

Though water hardness can be problematic, there are several ways you can prevent it and treat it. It is important to regularly test your water to help make sure it is at a good level. Water hardness is a common problem that many fish owners deal with.

What Is Water Hardness In An Aquarium?

The concept of water hardness in aquariums can be confusing and is often overlooked by fish owners. However, many fish can only thrive in certain hardness levels of water. It also affects the pH levels in aquariums.

Water hardness is the mineral levels in the water. Hard water will have a high dissolved mineral content. Soft water, on the other hand, has a low level of dissolved mineral content.

The most common water in mineral in water is calcium, also referred to as limestone. Over time, limestone can cause a white haze to form on your aquarium. In addition to limestone, magnesium is also another common mineral found in water.

Often referred to as general hardness (GH), the hardness levels are often higher in well water. Water hardness is typically linked to pH levels. If the water is hard, the pH levels are often high, it the water is soft, the pH levels are often low.

Most fish species will do well in moderately hard or slightly soft water. However, acidophiles and alkalophiles tend to be less tolerable.

Read more about: How To Reduce pH In An Aquarium

How To Soften Aquarium Water

If your pH levels are getting too high, you will want to soften your water. Softening aquarium water is an important part of keeping your water at a healthy level for your fish.

Fortunately, there are tests available to measure the hardness levels in your aquarium. These tests will allow you to determine whether you need to soften your water based on the needs of your fish.

You can buy water hardness test kits at most pet stores as well as online. You should test the hardness of your water on a regular basis to ensure that the levels are safe for your fish.

Reverse Osmosis

Reverse osmosis works to produce high-quality water that is free of chemicals, waste, and water hardness. The process demineralizes or deionizes the water to make it healthier for your fish and other aquatic life. It is one of the most effective ways to purify the water in your tank.

The process of reverse osmosis works by pushing water through a semipermeable membrane. This process removes up to 99% of impurities in water. However, reverse osmosis systems can be expensive.

Reverse Osmosis

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Peat Moss Filter

Peat moss can be added to your filter media to help lower the hardness in your aquarium. To do this, place granules of the peat moss into your filter. It works by binding calcium and magnesium ions, which in return softens the water.

Before adding it to the water, it is best to boil the peat moss before adding it to your aquarium to sterilize it for two to three minutes. Be sure to regularly replace the peat moss in your aquarium filter.

Water Softening Pillows

Water softening pillows are a quick and easy way to soften your aquarium water. They are a type of chemical filtration system that is particularly beneficial for small aquariums.

The softening pillows have ion exchange resins, which work to absorb calcium and magnesium, along with other soluble heavy metal ions. The exchange process works to release sodium ions as the minerals get removed.

Water softening pillows are reusable. All you need to do is soak them in a brine for two to four hours before returning them to your aquarium. Though they can be used in large aquariums, it will take much longer.


Driftwood is a great way to soften your aquarium water. It works similarly to peat moss as it produces acids that work to neutralize carbonate compounds. It is important that you use new, clean driftwood in your aquarium.

Before adding the driftwood to your water, boil and scrub it to remove any toxins. In addition to softening the water, your fish will also like the driftwood as a place to hide out in. It is an affordable and practical option that your fish will enjoy.


Rainwater is a free and effective way to reduce the hardness of the water in your aquarium. It is naturally soft and works to lower the hardness level when mixed into an aquarium.

However, you only want to use rainwater if you live in an area that doesn’t have high air pollution, as this will do more harm than good. Be sure to make the process as sterile as possible for the wellness of your fish.


How To Reduce Water Hardness In An Aquarium

Depending on where you live, you may have hard water from your tap. The hardness of water depends on the amount of dissolved minerals, such as calcium and magnesium. The hardness levels of your water will affect your pH levels, so it is important to monitor them.

Though some fish will do alright in hard water, you generally want to soften it if the hardness levels are too high. This will also help lower the pH levels to provide a healthy and safe environment for your fish.

The best ways to soften the water in your fish tank are to use reverse osmosis, rainwater, add peat moss to your filter, use water softening pillows and add driftwood. Each of these methods will create a healthy environment for your fish. In addition, you should regularly test your water to make sure the water isn’t too hard.

Do you have any questions regarding how to reduce water hardness in an aquarium? If so, please ask any questions regarding water hardness and how to soften it in the comment section down below.

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