How to Lower pH in Aquarium


How to lower pH in aquarium? Your fish will get enough oxygen in the tank with proper water pH level. They can thrive, be happy, and stay healthy! That’s why it is essential to check the pH level of your tank water regularly. At the very least, achieve between 7 and 8 pH level, depending on the type of fish and size of your tank.

In this post, we’ll discuss ways to raise or lower pH in your tank, what pH is, and how often to check it, among others. Let us begin.

How to Lower pH in Aquarium?

Before going any further, know that the pH level requirement of a tank depends on the fish you keep and your tank’s current pH level. You need to determine these things before deciding whether to raise or lower the pH level.

It is why less acidic water doesn’t always mean good. In this case, test your tank’s water before lowering or raising its pH level. Here are a few things you can do.

Change the water

Unchanged water for quite a while typically has a low pH level. You might have to change the water if your fish love pH of tap water. Changing the water will raise the pH level.

Consider 30 to 40 percent water change if you notice a deviating or fluctuating pH level. It’s effective in keeping pH level consistent besides raising it. Also, consider removing waste and uneaten food to lower the pH level over time.

Use rocks or substrate

Want to raise the water’s pH level? Add substrate or rocks to your tank. By doing so, you can raise its pH level. A variety of rocks is a good idea. You might also want to add crushed coral, petrified coral, or limestone. It’s an ideal substrate if you’re keeping African cichlids.

Add a driftwood in the tank

If the tank water’s pH level is high, lower it by adding natural driftwood. It will work to naturally filter the water especially if you’re not removing uneaten food and waste that lowers the water’s pH level.

The driftwood will remove the contaminants to lower the water’s pH level. Choose a course and fibrous wood. It’s better in filtering the tank’s water.

Driftwood can change and affect the water’s color. Ensure that you’re buying one meant for fish tank and not for reptile tank use. The latter’s driftwood is with chemicals. They are dangerous for your fish.

Add peat moss

Peat moss can lower the pH level of the water. It also clears out any contaminants in the tank and works as a natural filter. But then, it can cause water discoloration.

Before adding it to the tank, pretreat it. Soak it in a bucket of water for a couple of days before setting it up in your tank. Once done, soak it into the water directly.

For the best results, you might also want to place it in a filter bag or inside your tank’s filter. It will make the peat moss more effective in filtering the water and prevents you from throwing it when cleaning the tank.

Its amount depends on your tank’s size and the water’s current pH level. You can experiment and try different amounts until you figure what the most suitable amount for your tank is.

What is PH?

It’s the power of Hydrogen (H). pH level refers to the acid and base balance in water or a solution. Measurements range from 0 to 14.

  • Neutral = pH 7.0
  • Acidic has less than pH 7.0
  • Basic has more than 7.0

How Often Should I Check pH in Aquarium?

Do it once a month or every two weeks. By doing so, you can detect trends and changes before they become an issue later.

Have a logbook where to write the results and reread for reference later. pH level varies according to the time of the day.

Testing done at different times result to varying results. For this reason, check and test at the same time of the day.

Test the pH every time illness or death occurs. You must check the pH level if you started adding medication or treatment to the water as well. Perform another test on the last day of treatment and a week after it.

Tip: Do water changes when the pH level starts changing and not ideal for your fish.

Planning to buy new fish? Ask the seller what their tank water’s pH level is to find out if it is not much different with your tank’s current pH level.

Preferred pH of Common Freshwater Fish?

Different fish requires different water pH level. As fish came from bodies of water like rivers and lakes with a different pH level, the ideal pH levels differ from one specie to another.

Remember that pH is not static because it fluctuates and changes over time. There are also cases when it changes daily.

The tank water’s pH level drops at night and increases at daytime due to activities like photosynthesis and respiration.

It can also change as you add or remove fish, biological processes change, and you perform a water change. What’s the ideal pH level? Here are a few examples.

  • Hachetfish 6.0 to 7.0
  • Angelfish 6.5 to 7.0
  • Neon Tetra 5.8 to 6.2
  • Clown Loach 6.0 to 6.5
  • Zebra Danio 6.5 to 7.0


Hope you learned from this post on how to lower pH in aquarium and apply the tips to avoid problematic pH changes that will affect oxygen level in your tank and your fish’s health.

Nevertheless, pH is essential to your tank plant’s and fish’s wellness. Perform a regular testing, ideally every two weeks to spot any negative trends that will affect the health of your fish.

By using the tips above, you can raise or lower your tank’s pH level depending on your fish’s needs and size of your tank. Don’t be afraid to try the different options to know what works best for your fish and tank.

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