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All About pH

Everything you need to know about pH in your aquarium

The pH value of your aquarium is an important factor for the health and well-being of your fish and plants. The pH indicates whether the water is acidic, neutral, or alkaline. In this article, I will explain how to measure pH, what good pH values are for your aquarium, and how to keep the pH stable.

What is pH?


pH is the abbreviation of the Latin term potentia hydrogenii, which means hydrogen ion concentration. You can, of course, forget this immediately, but since I had to look it up myself, I thought it would be fun not to withhold it from you ;)


pH is based on a scale of 0 to 14, where:

  • pH 7 is neutral,
  • pH lower than 7 means acidic water,
  • pH higher than 7 means alkaline water.

The human body has a pH of around 7.3, which is slightly alkaline. So, when people talk about an "acidified body," it means you are below these basic values. (This, in turn, is good to remember)

It is important to keep a close eye on the pH because different fish species and plants require specific pH values to stay healthy.

African cichlids like Malawi, Tanganyika, or Victoria thrive in higher pH values. Meanwhile, in the Orinoco River in the Amazon rainforest, cardinal tetras swim in water with a pH of around 4.

So always check if your fish stock desires the same pH values and adjust accordingly. This will prevent many problems and diseases in your aquarium, with fish all too often dying long before their maximum lifespan.

MEASURING IS KNOWING: How to measure the pH value?

Measuring the pH value in your aquarium can be done in several ways:

  1. pH test strips: These strips change color depending on the pH value of the water. You briefly dip them in water and compare the color with a supplied scale. This is a simple and quick method, also widely used in swimming pools. The disadvantage is that they are not very accurate, and it can sometimes be difficult to estimate which discoloration corresponds to which value.
  2. Digital pH meter: Our strong preference. This measures the pH accurately by inserting a probe into the water. You can get a pH meter for about 30 euros, and they are much more accurate than a test strip. Make sure the glass bulb does not dry out, and you can use a pH meter for years.

It is wise to measure the pH regularly, especially in new aquariums or if your fish are behaving strangely. I always do this with regular maintenance, but with a Co2 computer, this is unnecessary.

Don't forget to calibrate your pH meter twice a year in test fluid. This keeps it accurate.

What are good pH values in the aquarium?

The ideal pH depends on the fish and plant species in your aquarium. Some guidelines:

  • Tropical freshwater fish: A pH between 6.5 and 7.5 is suitable for most popular species such as guppies, tetras, and catfish.
  • Amazon biotope: For fish such as discus and neon tetras, which live in soft, acidic water, a pH between 6.0 and 7.0 is ideal.
  • Cichlids (African Tanganyika/Malawi): These fish prefer alkaline water, with a pH between 7.5 and 8.5.

What are the risks of an incorrect pH?

An incorrect pH can cause stress, diseases, and even death in fish. Water that is too acidic can damage the mucous membrane of fish, while water that is too alkaline can affect the respiratory system of fish. Doesn't sound pleasant, does it?

Furthermore, certain plants may grow less well at an incorrect pH, and pH fluctuations can disrupt the biological balance in your aquarium. Rapid changes in pH are often even more harmful because fish have difficulty adapting quickly.

How do you stabilize the pH?

To keep the pH stable, there are several methods you can use:

  1. Water changes: Regularly changing water with water that has the same pH as your aquarium water helps prevent fluctuations. If necessary, use osmosis water to soften the water.

  2. pH buffers: Special chemical agents are available that you can use to raise or lower the pH and keep it stable. These agents add buffers that balance the pH. I am not a big fan of this as it also messes up your entire water chemistry. I prefer to look for natural solutions.

  3. Peat: Peat in your filter or as a substrate can lower the pH by releasing substances that acidify the water. This is a natural method that is especially useful for aquariums with fish from acidic water regions such as the Amazon.

  4. CO2 addition: For aquariums with many plants, you can add Co2, which not only helps plants grow but can also lower the pH because Co2 dissolves in the water and forms carbonic acid.

  5. Limestone or shells: To increase the pH value, you can add calcareous decorations such as calcareous stones or coral rock, which slowly release calcium into the water. Seiryu Rock or Elephant Rock are good examples of this. Do you want to know if stones contain calcium? Put a little vinegar on the stone; if it fizzes, it contains lime. Each type of stone on the site indicates whether it is inert (non-calcareous). This saves you the mess with vinegar ;)

Conclusion

Monitoring the pH value in the aquarium is important for the well-being of your fish and plants. By regularly measuring the pH and taking the right steps to prevent fluctuations, you ensure that your aquarium remains a healthy living environment.

Whether you have a soft water biotope such as an Amazon aquarium or a tank with African cichlids, a stable pH is one of the keys to success.



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