How to Make a Fish Tank Less Acidic?

How to Make a Fish Tank Less Acidic?

Here are 11 easy methods to make your fish tank less acidic. We have also added the causes of high and low pH in the aquarium.

How to Make a Fish Tank Less Acidic? You can make a fish tank less acidic by using some chemicals like baking soda, applying some useful techniques, and maintaining and cleaning your aquarium often. Low pH is not suitable for many fish species, and it can harm them in many ways. You should maintain the pH of the aquarium between 5.5 to 8.5.

The pH is critical to the health of the pet fish in the aquarium, and it is necessary to check it frequently to avoid harming them.

You should test the acidity of water at least every month, preferably every two weeks, and it is best to check it every week. Also, check it before adding new fish and when you are treating the fish tank with medications. You can easily control the aquarium pH levels.

How to Make a Fish Tank Less Acidic?

Most aquarium fish and plants can survive and tolerate change the tank’s conditions and water parameter. They are resistant to slight changes in water temperature and pH and can live actively in the fish tank.

Remember that not all are resilient, and some are too sensitive to even small changes. It is essential to do some research before adding fish to the aquarium.

Fish thrive and remain happy in the tank that has the same water conditions as their natural habitat. When you observe your fish are suddenly getting sick or inactive, there may be much reason.

One of these reasons is the change in water conditions, such as increase or decrease water pH. It is necessary to keep the match and balance the pH of the tank.

Too much acidity and alkalinity both can harm the fish and can even kill the fish. You have to be very careful while establishing and maintaining a tank that has varied fish and plants in it.

Drastic changes severely harm this small aquatic life, and you have to figure out the reason behind the disturbance to prevent damaging your fish. 

What is pH?

The term pH means the power of hydrogen, where H is the atomic symbol of hydrogen. The pH is the acid-base balance of a solution. The water consists of two molecules, hydrogen and oxygen, and its pH is 7, which is neutral. It means it contains an equal amount of hydrogen and hydroxide ions. 

What is the pH scale?

The pH scale can measure the acidity and alkalinity of a substance and solution, and you must use it to check and balance the pH of your aquarium. It is a scale that starts at 0 and ends at 14.

When the pH is greater than 7, the solution is basic or alkaline, and when the pH is less than 7, it means acidic. When there are more hydrogen ions, it indicates that the compound is acidic, and when there are more hydroxide ions, the solution is alkaline. The pH is a measurement that describes how acidic or basic a solution is.

How to check the fish tank acidity?

The best tool to monitor the pH of the fish tank is to use a pH water test kit. The kits are affordable, accurate, and convenient in use, and you can check using them on your own without any experience. You can also use digital meters, but they are too expensive. The most common kits are:

Reagent-based drip kit

The reagent-based drip kit is the classic and most common kit in use. Take out some water from the fish tank and add it into the tube, then add the reagent. Now observe the color the acidic water turns yellow to red while alkaline water turns blue to purple. 

Dip tests trips

Another way is to use a dip test strip, and it is also easy to use. You have to dip the strip in tank water and compare the color with the handy color table. You have to be quick in this process and check the result between 30 seconds to a minute.

It also shows other parameters in just one dip, such as nitrates, nitrites, ammonia, iron, carbonates, and even water hardness.

Harmful effects of high acidity levels in a fish tank

High acidity or low pH has a severely damaging and disastrous effect on the fish of your aquarium. High-acidity is fatal and poisonous to the inhabitants of the fish tank and can bring them several diseases. The most common issues are:

Effect on fish


Low pH means there are too many acids in the water, and they cause burns or lesions to the fish’s skin. Young fish are more sensitive and are more vulnerable to skin burns and lesions in a highly acidic environment.

It can kill all the fry and eggs in the aquarium. Also, the fish skin starts producing excess mucous and deteriorating the skin of fish.

Abnormal behavior:

Due to a high acidic environment, the fish start exhibiting abnormal behavior and acting irritable. They may try to jump out of the tank or swimming frantically and become sick.

You may observe them scratching, twitching, shimmying, and flicking against objects in the tank. This behavior is a sign of toxins or unnecessary chemicals in the tank. 


The acid damages the gills of fish, rendering them unable to breathe and resulting in grasping for air. This state is fatal for your tank fish, and if the situation continues, the fish will die. The fish may try to breathe on the water surface because they can not survive in the highly acidic water.

Eyes damage:

The eyes are sensitive body organ of both humans and animals and the acid damage them irreversibly. Your tank fish will lose their vision due to the damage which the acid causes to their eyes.

Effect on water chemistry

The pH impacts water quality and water chemistry. Too low pH can destroy the whole water chemistry of the tank. When the pH drops below 6, your tank’s nitrification bacteria begin to die.

These bacteria are responsible for keeping the tank ammonia and nitrites level at zero ppm. In the absence of these bacteria, the ammonia and nitrites level increases in the tank. These compounds are toxic and can result in killing the fish.  

Effect on plants

Similar to fish, the aquarium plants also suffer from burns in low pH. The plants are usually not too hard, and acid can burn their leaves and result in dead plants in the tank.

Methods to make a fish tank less acidic

You can not rapidly change the water parameters of the tank as it may stress and shock fish. A gradual increase in alkalinity is preferable to prevent harming the fish. Several methods and tips help you lower the acidity of your aquarium.


Substrate plays a vital role in decreasing your tank’s acidity. It is better to add crushed corals or dolomite gravel as the substrate to balance the pH.

Limestone and petrified coral will also help you achieve the goal. If you can not lay down the coral substrate, use a bag full of crushed corals and place it behind other objects.


Aeration is essential to maintain the water quality and water parameters of your fish tank. You have to provide adequate oxygen to drive down the carbon dioxide levels.

Increase as much aeration as you can in your aquarium to purify water. You can add an air pump or air stones as well to increase oxygenation. You should regularly clean the aquarium air stones.


The best chemical to neutralize or increase alkalinity is the use of baking soda. It supplies bicarbonates in the tank that will make a fish tank less acidic.

Add one teaspoon of baking soda per gallon, which is safe. There are also several commercial buffers available in the market to decrease acidity in the aquarium.

Frequent water changes

Water change and renewal are the keys to a healthy aquarium environment. Change 20-25% of the water after every 2 to 3 weeks to avoid accumulation and buildup of wastes. More preferably, change a small amount of water daily.

Activated charcoal

Activated charcoal reduces tannins in the tank and helps increasing pH. If your tank filter does not has carbon media, you should add it to the filter. You can also make a fish tank filter less powerful.

Shells and rocks

Limestone shells and rocks contain carbonates that help to increase the alkalinity of the tank. They also increase the beauty of your aquarium. Decorate it with beautiful seashells and mineral rocks to raise pH. The seashells dissolve slowly, so wait for a week before checking the pH.

What is the ideal pH for the fish tank?

All species are different and require different acidity and alkalinity level in the tank. You have to research and collect information about the correct pH level for the inhabitants of your tank. Usually, the desired levels range between 5.5-8.5.

The ideal pH range for freshwater aquarium

Freshwater fish live and thrive in a pH ranges from 5.5 to 7.5 because it matches their natural habitat. They like to live in slightly acidic water and can not live in alkaline water.

pH range for saltwater aquarium

The pH of a saltwater aquarium should range between 7.5 to 8.5 as these fish prefer alkaline water. They can not survive in acidic water because of their natural alkaline habitat. They like to live in hard water as the water hardness directly relates to water pH.

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