How To Lower KH In Aquarium – 5 Best Tips And Tricks

Last Updated on January 21, 2022 by Fabiola L.

These are the best tips and tricks on how to lower KH in aquariums when it comes to its excessive concentration. Click to learn more.

Carbonate hardness acts as a blocker between the acids and the pH level, which occur naturally in the aquarium. KH plays a major role in balancing pH levels inside your tank. Its concentration varies, and this often results in its surplus or deficit. This is by no means good for the overall health of your aquarium.

When the pH level is escalating, it is necessary to lower the KH level to preserve your aquarium inhabitants. Wondering how to lower KH in the aquarium? Here are our top 5 tips and tricks to solve this problem.

What Is Aquarium KH?

Carbonate hardness (abbreviated KH) is a measure of carbonates (CO3) and bicarbonates (HCO3) dissolved in water. Simply put, it’s a protective barrier that surrounds the pH in your aquarium, and prevents the tank from becoming poisonous to both fish and live plants. It’s also often called acid neutralizing capacity and total alkalinity.

Why Is KH Important To Your Aquarium?

Deviations in the amount of KH pose a risk of rising pH levels. This can have a pretty devastating effect on the overall health of your aquarium. Understanding and regularly monitoring KH levels in your aquarium is key to creating a healthy environment.

Regarding the level:

  • 7 indicates that the pH level of the water is neutral,
  • A pH value below 7 indicates that the water is acidic,
  • A pH above 7 indicates that the water is basic.

The right pH level of your water depends on the needs of your aquarium. Some will prefer slightly acidic and some slightly base water. So, try to inquire about these details before buying fish.

Should It Ever Be 0?

Owners of freshwater aquariums have probably heard so much advice on how to reduce KH in an aquarium to avoid regular monitoring. It’s a delusion that can be toxic and devastating to both, plants and fish.

Remember – the pH and KH levels are connected. The more things you add to your aquarium, the more the chemical structure of the water changes. So, keep an eye on the KH and pH levels. If you change the pH level, you have to adjust the KH level, and vice versa.

The Best KH Level For Your Tank

Freshwater KH:

  • Tropical Fish Tank (4-8 dKH),
  • Shrimp Tank (2-5 dKH),
  • African Cichlid Tank (10-18 dKH),
  • Discus (3-8 dKH),
  • Planted Tank (3-8 dKH),
  • Brackish Tank (10-18 dKH),
  • Pond (4-8 dKH).

Saltwater KH:

  • Saltwater Tank (8-12 dKH),
  • Reef Tank (8-12 dKH).

How To Lower KH In Aquarium – In Detail

As mentioned earlier, KH helps prevent the pH of aquarium water from dropping. Surely like most other hobbyists you are wondering how to lower KH in an aquarium. The math is simple; you need to make a balance between KH and pH. While increasing KH is fairly simple, lowering KH in an aquarium will be a bit more complicated.

Jump in and learn the best tips and tricks on how to lower carbonate hardness.

Learn more about How To Raise Kh In A Freshwater Aquarium?

Converting KH To CO2 With Acid Buffers

Acid buffers are used to convert KH to carbon dioxide (CO2). This ultimately results in lowered KH and pH levels. They are most commonly used in planted tanks where plants remove excess carbon dioxide from the water.

On the other hand, even if you don’t have plants there is the possibility of an overdose that can increase CO2 but also drastically lower the pH level. This in many cases will result in dead fish.

To avoid terrible outcomes, follow the instructions and always adjust the dose of the acidic buffer.

Distilled Water

Distilled water is obtained first by heating until it turns into steam, then by passing it through a cooler and into a storage container. Such water is almost absolutely clean of impurities, and of course without KH. You can find it at almost every local store in gallon jugs.

As already mentioned, KH-free water is still not a good aquarium environment. Therefore, it would be good to mix distilled with tap water as the aquarium needs some amount of KH.

This is an effective way of lowering KH in aquariums.

Creating Pure Water With RO/DI

Did you know that you can create a clean aquatic environment in your aquarium with just one of the following units?

  • Reverse Osmosis (RO) System
  • Deionization (DI) Filter

Both are used to produce clean water without KH. However, keep in mind that it’s still necessary to mix distilled with tap water. The DI / RO water will proportionally lower the KH in relation to the amount of water you mix.

Creating Pure Water With RO/DI

Learn more about: How To Reduce Water Hardness In An Aquarium

Indian Almond Leaf & Tannin Release

Adding Indian almond leaf is one of the most popular ways on how to lower KH in aquariums. It’s particularly popular in freshwater and betta tanks.

After the addition, Indian almond leaves begin to decompose inside the water and then begin to secrete tannins (tannic acid). Then the tannin begins to consume KH in the aquarium and reduces its concentration.

Monitor the situation so that there is no complete deficit. That’s not good at all. As with everything else, balance is key to success.

Peat moss & Tannin Release

Peat is obtained by drying and grinding with peat moss. You can use it in your aquarium by putting it in a mesh bag and then in a filter. Just like the Indian almond leaf, peat moss releases tannins that eventually lower pH and KH levels in the water.

This is another very effective method of reducing KH in aquariums. Also, be sure to buy a variety safe for aquarium use. Those intended for gardening contain a large amount of toxic compounds that can be fatal to all the fish and plants in your aquarium.

To Wrap Things Up

KH plays a vital role in maintaining stable water parameters. Its high or too low concentration regularly stresses your fish and plants and causes all sorts of problems.

Do you have any tips on how to lower KH in aquariums? Let us know in the comments below!

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