How To Increase Water Hardness In Freshwater Aquarium?

Hi, this is your friend Clifton Ervin, the founder and chief editor of this site, Aquariumwolf. I completed my graduation in marine biology and became...Read more

Saltwater fish and plants come in diverse colors that you may love to keep in your aquarium. But these marine fish and plants need a higher level of salinity in the water (hardness) than in freshwater, as they are used to living in the sea.

So, if you plan to foster saltwater fish in an aquarium, you must ensure the aquarium water is habitable for those fish.

However, maintaining a habitable level of salinity (hardness) in aquarium water can be costly when the naturally present water in your area is freshwater, and you buy salt water from an aquarium shop.

But there are some water chemistry tricks to convert freshwater to saltwater.

And in this discussion, we will tell you how to increase water hardness in freshwater aquarium so that you can foster those marine fish in your home.

How to Increase Water Hardness in Freshwater Aquarium?

In terms of water chemistry, there are many ways to increase the hardness of freshwater aquariums, such as using chemical additives, using crushed coral, aragonite, and some other methods. But knowing how these methods work; when to apply which method and what would be the ideal practice to increase water hardness would always be the safest road to go.

How To Increase Water Hardness In Freshwater Aquarium

Because saltwater fish and plants are quite expensive, you may not want to see dead plants and fish inside your aquarium.

So, before we learn the ways to increase the water hardness in your freshwater aquarium, let’s know a bit about water hardness, what GH and KH levels are, and why PH level is also important.

What is Water Hardness, GH, and KH?

According to the U.S. Geological Survey, the quantity of liquified magnesium, calcium, and other minerals in water defines water hardness. Simply put, hard water contains a higher concentration of dissolved minerals than normal water.

So, we can say that if water from a source contains a high grade of dissolved calcium, magnesium, and some other materials, then we can call the water harder than normal water.

We can divide water hardness into two parts: one general hardness (GH) and the other carbonate hardness (KH).

General hardness (GH) and carbonate hardness (KH) are the most significant indicators for measuring the number of dissolved minerals in the water.

GH, or general hardness, indicates the amount of magnesium and calcium ions in the aquarium water.

The quantity of bicarbonates and carbonates in your aquarium water is measured by KH (carbonate hardness).

Basically, water hardness (GH & KH) is calculated by how many minerals are available in the water; the most common units are milligrams per liter (mg/L) and grains per gallon (gpg).

What is PH and Why It is Important?

Your PH level determines how basic or acidic your water is by measuring the number of hydrogen ions present within it.

Basically, PH is important because it tells us whether your aquarium water is too hard or not. Because if the aquarium water becomes too much harder, the fish inside it may get hurt.

Ways to Measure Water Hardness (GH, KH) and PH Level

According to WikiHow, there are several methods and test kits that come on the market to measure the GH and KH level of the water. And you can use these 3-step guides to measure your water’s PH level as well.

What Hardness Level and PH Level Is Best for Saltwater Fish?

Most saltwater fish and plants need a general hardness level of 6.5 – 8.5 °dKH, but it actually depends on what type of fish and plant you buy.

What Hardness Level and PH Level Is Best for Saltwater Fish

Basically, KH hardness is directly related to the pH level. So for most saltwater fish and plants, a pH level of 8.0 would be perfect. But it will depend on the specific sea fish you get.

You must check what pH rate is required for your marine fish and plants.

ph rate to measure the hardness level of aquarium water

So, once you measure the hardness level of the water you will get an idea of how much will you have to increase the hardness level of your aquarium water.

Here are the possible ways to increase water hardness in your freshwater aquarium: (first let’s talk about increasing GH, and then we will cover KH)

How to Increase GH and KH Levels in Your Freshwater Aquarium?

There are many ways you can increase the GH and KH level in your freshwater aquarium:

1. Use Chemical Additives

Using chemical additives is the easiest way to increase the hardness of the water. Because you can easily buy those additives online and those additives are really easy to use.

Such a reputable additive is Seachem Equilibrium which you can use to increase your water’s GH level.

The main minerals in this product are calcium sulfate, potassium sulfate, and magnesium sulfate, all of which are crucial for the health of plants and fish.

This product does not contain any form of sodium chloride, so it becomes a safe option for increasing GH levels.

Seachem Equilibrium works best for RO (reverse osmosis) water and can also be employed sparingly to increase the GH of tap water.

Another fantastic product from “SeachemAlkaline Buffer, which you can use to raise the KH level of your aquarium water.

Alkaline Buffer also contains a balanced amount of sodium bicarbonate, which has been found to be beneficial by thousands of users.

2. Add Crushed Coral

Crushed coral comes from dead coral reefs and because of that, it contains a large amount of calcium carbonate. That’s why adding crushed coral to your freshwater aquarium will make it harder.

On the other hand, adding crushed coral will raise both the water’s general hardness and carbonate hardness because GH and KH are positively present in crushed coral.

However, you should be aware that the pH increases with increasing KH levels.

And adding the crushed coral to your aquarium is quite easy. You just have to place your crushed coral in a media bag, or you can combine it with your gravel.

3. Adding Limestone

Also, the hardness of the freshwater aquarium can be boosted by adding limestone.

Because, limestone contains calcium and other helpful minerals, when it releases them into your water, it boosts the hardness.

4. Add Aragonite

You can also add aragonite to your freshwater aquarium to add hardness because it also contains calcium carbonate, as found in crushed coral.

Basically, aragonite is available as rock or sand, and adding it to your aquarium is easy. For instance, oolitic, a kind of aragonite that is mined from tropical oceans, is the ideal type to improve the hardness of your water.

Oolitic aragonite has a spherical shape and somewhat flows into the water, which means the substrate is ideal for your fish.

5. Add Baking Soda

Adding baking soda can also increase the water hardness level because baking soda contains sodium bicarbonate.

But you should only use baking soda if you need to increase the KH level or the carbonate hardness of your water.

Caution: If your fish and plants can not live with the presence of sodium in the water, you should not use baking soda to increase the hardness of freshwater.

6. Add Epsom Salt

Just like other techniques, adding Epsom salt would be a great way to increase the hardness of a freshwater aquarium.

Epsom salt contains magnesium sulfate, which can help you increase your general hardness level, or GH.

But Epsom salt can only increase the magnesium, so if you need too much hard water, adding Epsom salt alone would not be preferable.

Things You Should Remember While Increasing Freshwater Hardness

Here are a few important things you should remember whenever you go to increase the hardness in a freshwater aquarium:

First, Know how Much Hardness You Need:

Before you make your water hard, make sure you know about the fish and plants that you want in your freshwater aquarium. Because different types of sea fish and plants require different levels of hardness.

And if you do not maintain the exact level, your fish may not survive and your money may be wasted.

Check the Hardness of Your Regular Water Resources:

According to USGS, and the area above, many individuals have naturally hard water. This is typically true for geographic locations that get their drinking water from limestone-containing rivers.

So, before you use any method to increase your water hardness, check your daily water resources, such as tap water. If you find the exact hardness, then you will not need to apply any method. Isn’t it great?

Frequently Asked Questions

Still, if you’ve queries about how to Increase water hardness in freshwater aquariums, read the following FAQ section and get most of the answers to those queries.

Are KH and Alkalinity the Same Terminology?

Basically, Alkalinity measures the amount of bicarbonate and carbonate in the water, which is similar to KH or Carbonate hardness. But in water chemistry, they are measured in different units, meg/L for alkalinity, and dKH for KH. But at the end of the day, both are the same.

What Is the Relationship Between PH Level and Alkalinity?

pH is a measure of the amount of acidity in the water. So, the more acidic the water is, the lower the pH. And higher pH means lower acidity, which also refers to the higher carbonate and bicarbonate. The higher the pH, the more alkaline the water source.

Should I Check the Water Hardness if I Keep a Saltwater Aquarium?

Actually, the answer is quite controversial. But most aquarium specialists and water chemists have agreed that you must check the water hardness once a week. Because those marine fish and plants inside your aquarium need special care, and if the water hardness goes out of their habitable zone, you may find yourself in trouble.

Final Words

Yes, if you do not want to buy saltwater from an aquarium shop, then learning how to Increase water hardness in freshwater aquarium is a worthwhile lesson to learn.

In this discussion, I tried to tell you most of all the possible ways to increase the hardness of water, so that you can now convert freshwater to saltwater and foster marine fish at home.

But, make sure you check your water hardness and understand which type of fish requires how much GH or KH increase.

Hi, this is your friend Clifton Ervin, the founder and chief editor of this site, Aquariumwolf. I completed my graduation in marine biology and became an Ichthyologist. One of my favorite hobbies is aquarium keeping; therefore, I love to talk about fish keeping, breeding, food behavior, etc., and much more relevant to aquarium maintenance. I have created this site Aquariumwolf, to share my 20 years+ of experience and knowledge with all new to this journey.

More Posts

Leave a Comment