How to Lower pH in The Aquarium? 5 Recommend Solutions

Lowering or increasing pH in aquariums should be done before adding any fish. In this article, we will mainly focus on How to lower the pH in the aquarium.

Not every fish keeper keeps track of their aquarium pH. Beginning of my fish keeping, I do not even bother to keep track of the pH. You can count this as a beginner’s mistake.

There is a reason behind this mistake. Most of the time captive-bred fish are resilient, tolerant of a wide range of pH levels, and slightly alkaline.

In this article, we will learn how to lower the pH in aquariums.

If your fish are not showing signs of distress, then you can leave the pH as it is. Try to keep those pH levels consistent.

How to Lower pH in The Aquarium?

Let us see what is the recommended methods of lower ph in the aquarium

Catappa Leaves

Catappa Leaves are also known as Indian Almond Leaves. They are also known as ‘the poor man’s water conditioner’, due to their ability to alter water conditions in an aquarium.

When they decompose in your aquarium, they release tannins. If you do not want to have left in your tank, you could soak the leaves separately and add the strained water to the tank during a water change.

They will safely lower the pH in the tank. Catappa leaves are like Peat Moss and Driftwood, they will turn your tank yellow or brown.


Driftwood also helps to reduce the pH level of the tank. Like Catappa Leaves and Peat Moss, Driftwood will release tannins into your tank.

Driftwood also changes your tank watercolor into yellow or brown. Though the discoloration will not harm the fish or plant.

Do not use any kind of Driftwood you find. Driftwood is also used for reptile keeping. You should not use that Driftwood for your aquarium.

It may contain chemicals that are harmful to fish. You should also make sure there is no dirt or debris on the Driftwood. We can also boil it in salt water to sterilize it.

Peat Moss

This is also a wonderful natural way to safely lower your aquarium’s pH. It will also discolor the water.

They just need to stay in your tank for effect. Only dipping it in the water won’t do anything. Buy pellets or chunks of Peat Moss and place them in your filter.

It releases tannic and gallic acids, which will attack the bicarbonates in the water, reducing its hardness and pH.

It is hard to say how much you need to use. It depends on how hard your water is and the quality o Peat Moss.

You can use a small clump and monitor your pH. You can then also add more if it is needed.

Find more about Freshwater Fish.

Water Changes

Water changes are one of the most effective ways to lower the pH in your fish tank. By removing a portion of the water and replacing it with fresh water, you can slowly lower the overall pH of the tank.

Water changes also have the added benefit of removing toxins and wastes from the water, which can improve the health of your fish.

If you are concerned about lowering pH too quickly, be sure to remove any plants or animals that are sensitive to changes in water chemistry before making pronounced changes.

With a little patience and diligence, you can easily lower the pH in your fish tank using natural methods.

Reverse Osmosis Units

Reverse Osmosis Units can also lower the pH in your fish tank is to use a Reverse Osmosis Unit (ROU).

Reverse osmosis units work by passing water through a semipermeable membrane, which removes dissolved minerals and other impurities. This process lowers the overall pH of the water.

How to Lower pH in Fish Tank With Baking Soda?

You can also use baking soda to lower the pH in an aquarium. The easiest and most common way to lower pH is by using baking soda, also known as sodium bicarbonate. Baking soda will immediately start to lower the pH of your tank water.

Start with 1 teaspoon of baking soda per 10 gallons of water, and monitor the pH closely over the next few days.

If necessary, you can add more baking soda to lower the pH further. Just be sure not to add too much at once, as this can cause sudden swings in pH that can be harmful to your fish.

What is pH?

Hopefully, we all remember our teacher mentioning water (H2O) is made up of hydrogen and oxygen molecules. In pure water, there are an equal number of hydrogen ions (H+) and Hydroxide ions (OH-). When a basic (alkaline) or acidic substance dissolves in aquarium water and any other water, it will alter the balance of ions, resulting in a change in the pH.

Keep in mind pH scale is not a linear measurement. It is a logarithmic scale; which means each unit is greater than the last one by a factor of 10.

pH 5 is an increase of 10 over pH 6 in terms of acidity. pH 9 is an increase of 10 in alkalinity over pH 8. pH 7 is a neutral balance of H+ and OH- ions.

It appears to be a small change in pH using a test kit, but in reality, it is a significant change in chemistry. It may have drastic effects on your tank ecosystem.

Symptoms of High pH in Fish Tank

When it comes to keeping fish, water quality is key. In addition to making sure the water is at the right temperature and has the right levels of oxygen, it’s also important to maintain a healthy pH balance.

A pH that is too high or too low can cause a variety of problems for fish, including stress and disease.

Symptoms of high pH in a fish tank can include gasping at the surface, increased respiration rate, lethargy, and lack of appetite.

If left unchecked, high pH can eventually lead to death. Maintaining a healthy pH balance is essential for any fish keeper, so it’s important to be aware of the symptoms of high pH and how to correct them.

Symptoms of Low pH in Fish Tank?

A low pH in your fish tank can have a number of negative impacts on your fish. The most common symptom is lethargy, as the fish’s body is unable to properly process the food it eats.

This can lead to weight loss and a weakened immune system. Low pH levels can also cause mental stress, which can lead to aggression and other behavioral problems.

In extreme cases, low pH levels can be fatal. If you notice any of these symptoms in your fish, it is important to test the pH of your tank and take steps to correct the problem.

What Causes High pH in Fish Tanks?

Most fish thrive in neutral pH water, neither too acidic nor too alkaline. However, sometimes the pH in a fish tank can become imbalanced, leading to high pH levels.

There are a few possible causes of this problem. First, if the tank water is too hard, it can cause the pH to rise.

Another possibility is that there are too many algae in the tank, which can also lead to high pH levels.

Finally, if the tank is decorated with limestone or dolomite rocks, they may slowly increase the pH of the water.

If you suspect that your fish tank has high pH levels, it is important to test the water and take steps to correct the problem. Otherwise, your fish may become stressed or sick.

What is the pH scale?

The pH scale can determine the acidity, alkalinity, or neutrality of water. pH is measured on a scale of 0-14, 7 is neutral, below is acidic and higher is basic (alkaline).

PH-Scale,Lower pH in The Aquarium
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As mentioned above each number on the scale represents a difference of 10-fold. For example, if my aquarium has a pH of 6 it is 10 times more acidic than a tank with a pH of 7. Or if it is got a pH of 5, It is 100 times more acidic than a pH of 7 and vice versa.

Tools to Monitor the pH in the aquarium

Before adjusting our aquarium water, we just need an accurate reading of pH.

We can use the classic test of the pH reagent-based drip kits like API’s pond test. Add water into a tube and the reagent, you can watch as the water changes color.

Match the watercolor to an included chart and you will know how acidic or basic your water is. These kits are not very expensive, are easy to use, and are also entirely accurate.

The pH strip tests are also common. This test is even easier than reagent-based tests. We can simply dip our strip into the aquarium and compare the result to a handy color within 30 seconds to a minute.

Test strips like Capetsma’s 9-in-1 aquarium test strips can even simultaneously test pH, kH, nitrate, nitrite, ammonia, and iron in a single swipe.

When should I Lower the pH in the aquarium?

We usually tend to raise or lower the pH in the aquarium for the health of living fish and plants. Different fish and plants come from different regions of the world.

They have their stable pH recommendation. If you keep tropical, equatorial regions like Brazil or Southeast Asia, many of those fish thrive in acidic water. Before adding any fish you should check the pH of your aquarium.

Hey, I am Shuvradeb Biswas a content writer. Fishkeeping is my hobby. There are many problems I faced during my first fishkeeping. So, I made the blog to help new fishkeepers.

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