How to Lower pH in The Aquarium Guide

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

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, and resulting in the change of the pH.

Keep in mind pH scale is not a linear measurement. It is a logarithmic scale; 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.

What is the pH scale?

The pH scale can determine acidity, alkalinity, or neutral 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 must 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 add 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, easy to use, and also quite accurate.

The pH strip tests are also common. This test is even easier than the 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, iron in a single swipe. This one is also good for general water quality monitoring.

We can also use digital meters. It shows the number, not the color charts. Some of them even show the temperature in seconds.

When shuld I Lower pH in the aquarium?

We usually tend to raise or lower 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.

Rcommended Methods of 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 mans 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 leaves in your tank, you could soak the leaves separately and add the stained 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 chang 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 saltwater 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 the 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.

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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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