How to Increase Water Hardness in Aquariums?

It is essential to give your fish the right water conditions in order to keep them happy and healthy. In certain situations, this may imply increasing the hardness of the water in your aquarium. So, how can you make aquarium water harder?

In order to increase water hardness, you can add calcium and magnesium ions to the water. One way to do this is by using a water hardness increaser, which is a commercially available product that contains calcium and magnesium salts. Alternatively, you can add crushed coral, limestone, or other mineral-rich materials to the tank or filter. It is important to monitor the water hardness levels regularly and make adjustments as needed to maintain a stable and healthy environment for your fish. It is also important to note that different fish species have different water hardness preferences, so research the requirements of the specific fish species in your aquarium to ensure their optimal health and well-being.

If you don’t know how to increase water hardness, you can do it by using tap water, adding corals, or adding aragonite.

What is Hardness?

In case you do not know, In an aquarium, hardness is a measurement of dissolved minerals in the water, typically calcium and bicarbonates. These minerals tend to buffer water’s pH, making it more resistant to pH changes. As a result, the majority of aquarium fish who prefer hard water prefer water with a higher pH. Never use water softened by domestic water softeners in aquariums, even for soft-water fish. Home water softeners replace calcium and bicarbonates with other minerals, making the water even less compared to what a fish would encounter in the wild.

Related Post: How to Change Water in Fish Tank?

Ways to Increase the Hardness of your Aquarium Water

Using Tap Water

When it comes to aquarium water quality, you should always search for hard or severe levels. If your tap is more than “moderately” complex, there’s no need to go any further because this might lead fish to lose their appetite and plants to die off soon, leaving both parties with less-than-ideal living circumstances.

This explains why it is critical to replace your tap water on a regular basis. This will improve the conditions in your aquarium, allowing your aquarium fish and plants to survive indefinitely.

Use of Tap Water

You may be shocked to hear that utilizing tap water in your aquarium provides a number of advantages. One notable benefit is that it is straightforward and does not necessitate the use of any specific chemicals or processes. Despite the fact that it is a modern approach, it is not always the best. If your water is soft or hard compared to what comes out of your tap, try several methods.

Using Crushed Coral

If you want to raise the hardness of your water using crushed coral, you should know that it will improve both the general hardness and the carbonate hardness. There is no alternative explanation other than the fact that crushed coral includes both GH and KH. It is important to note that the greater the KH level, the higher the pH.

Using Crushed Coral

While you may dislike this transition, it is frequently a deal breaker for cichlid tanks that like hard water with a high pH.


Aragonite, which resembles calcium carbonate in its most soluble form, may teach aquarium enthusiasts a lot. Once added, it will affect your aquarium and is available as both rock and sand.


It’s no surprise that aragonite is so well-liked given its stunning, crystal-clear color and high luster to preserve the pH balance of your aquarium water. It only dissolves in freshwater and functions best in warm solutions, so it does have some drawbacks.

The best kind of aragonite to use to harden the water in your aquarium is oolitic, aragonite which comes from the ocean and has been fashioned into spheres. It liquidizes with very little flow, making it ideal for any kind or size of aquarium fish that require higher activity levels.

The Bottom Line on How to Increase Water Hardness in Aquariums?

Aquariums are a fantastic way to bring nature indoors, but they may be challenging to keep clean. Maintaining things properly is essential if you don’t want to harm any of your fish or plants.

Of course, this is all there is to know about increasing aquarium water hardness. Even while I claim that the aforementioned techniques for increasing aquarium water hardness are tried-and-true, keep in mind that there are times when your fish may not really require them.

Use a water filter with a media bed of either crushed coral or aragonite to improve the hardness in an aquarium. These minerals will aid in increasing your tank’s carbonate and pH levels.

Similar Posts