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Effects of pH in an Aquarium - Aquafishcare

Updated: Feb 1, 2023

What is PH? And why Maintaining the Ph level in an Aquarium is very challenging. Is it that important for the well-being of the fish? And how to sort things out. This article will make it easy for readers to understand without much scientific jargon to get confused.

Beginning of a problem

When I was planning to buy my first Aquarium many years ago, everything seems normal as per the shopkeeper's advice except with no information on ph requirement. I never thought of ph levels, nor any other jazz going into the Aquarium. I am sure all beginners will relate to what I just said. All hell broke loose when my fish started dying. So went back to the shopkeeper for advice, he told me I must have brought some infected fish from somewhere else that must have infected others or chlorine issue, water change issue, etc, but no ph information was provided. I did not know what to do. Started to gather information on, why fish die? So here I would like to help my fellow hobbyist in knowing the importance of maintaining Ph level to reduce the stress level in fish.

What is pH? Reason for a change of pH in an Aquarium

pH is nothing but “ the power of Hydrogen” Water is composed of hydrogen and oxygen atoms (H2O) Ph level in a tank which is a controlled environment keeps on changing, so much so the ph level can drop during the night time, even introducing new fish or even introduction of décor can alter the ph. Changes in the ph have consequences for the tank's inhabitants, especially the young and the sick fish. So it's very important to understand the ph level for the well-being of the inhabitants in an Aquarium. We need to understand the basic nature of a variety of fish from different regions and their Ph levels. That is why it is very important not to mix up different fish from different regions. Like fish belonging to the Amazon, the region should not be mixed with the African species and vice versa. The Amazon fish requires an Acidic Ph level between 6.5 to 7.0. Anything above 7.0 is considered Alkaline. The Ph Level for African cichlids especially the Malawi cichlids is above 7.2, I have personally kept them between 7.2 to 7.8 without any problem. Marine fish requires a ph level above 8.0

Generally, An ideal level of ph level to be maintained is between 6.8 to 7.8. Following is the desirable ph level for different species. This level is considered a balanced level for most of the fish in an Aquarium.

Following is the desirable ph level for different species

· Angelfish 6.5 - 7.0

· Goldfish 7.0 - 7.5

· Harlequin Rasbora 6.0 - 6.5

· Plecostomus 5.0 - 7.0

· Silver Dollar 6.0 -7.0

· Zebra Danio 6.5 – 7.0

· Neon Tetra 5.8 – 6.2

· Malawi cichlids 7.2 to 8.0

· Arowana 5.5 to 7.0 ( It prefers slightly Acidic for better coloration)

· Flowerhorn 7.4 to 8.0

One small piece of advice is not to tamper with what is working for you irrespective of the fish that you have. Don't try to fix things if it's not broken. If you can come to know the ph level of the fish in a shop, it will save your fish as this is the time when the death rate is high. For example neon tetra fish, I have experienced that neon tetra fish is too sensitive to water change and the pH. Discuss is also sensitive to water change and pH. Remember with every addition of fish to the tank, there is additional pressure on the biofilter which in turn reduces the ph level, that is why you need to change the water of an Aquarium which will increase the ph level and also good maintenance is a part of providing good health to the fish.


In the long run, ignoring the fluctuations of pH level will weaken the fish's immune defence, increasing the stress level in a fish affecting its overall health thereby leading to its death.

Altering the pH levels

Altering the pH levels

There are many ways to alter the ph levels. I have experimented with bringing the ph level from alkaline to acidic (below 7.0) by introducing driftwood which pleco loves to graze on it. If you want to increase the ph level to alkaline ( Above 7.0) have crushed corals put in your tank. My favorite was Caribsea sand for cichlids (never did my ph level go below neutral), Ph level for my cichlid for 3 years in a row was between 7.2 to 7.4. African Cichlid Mixes™ from caribsea also resist the eventual downward drift of pH in long established or crowded systems. My African Malawi Cichlids thrived in the water condition provided backed by good quality food and filtration. There are different buffers to alter the pH of the water in an aquarium. There are certain buffers to create a conducive environment for the inhabitants of the tank like the Malawi buffer, and the Discus buffer from Seachem.

Seachem has got a wide range of buffers to replicate different environments like the Malawi buffer, and Tanganyika buffer, it also has buffers to maintain an Acidic and alkaline environment, recommended to be used along with a neutral buffer to get the desired result.

For Planted Tank

If there is an excess of algae in the planted tanks or sliminess on the glass or the rocks, there can be a rise in the Ph level which is disliked by many fish. This can be taken care of by doing regular maintenance of the tank. Algae is the biggest problem in the tank. I have written a blog about my own experience of controlling Algae in the planted tank.

Testing the pH levels

Testing the Ph levels

There are different test kits to measure the Ph levels of the water in the Aquarium like the seachem pH test kit, Hanna's HI98107 pHep® pH tester displays readings with 0.1 pH resolution, ±0.1 pH accuracy, and a range from 0.0 to 14.0 pH. I have personally used both of the above and are very easy-to-use ph test kits. If you are using a Ph test kit. It is advisable to test the waters once a month. Or best even when introducing new fish to the Aquarium. Try and check before and after introducing the fish. Check for any changes in the pH level of the water. Also if the water was treated with medicine do the checks before and after and bring it to the desired level of PH by doing water changes gradually.

The Fluval pH test kit is another effective test kit that comes to my mind, having a pH Wide Range of, 4.5-9.0 (100 tests).

When to Use the testing Kit

It is advisable to test Aquarium water once a month. Or best even when introducing new fish to the Aquarium. Try and check before and after introducing the fish. Check for any changes in the pH level of the water. If the water was treated with medicine do the checks before and after and bring it to the desired level of pH by doing water changes gradually. Even if there is a fatality in an Aquarium there is a good possibility of fluctuations in the pH level. Please do the testing of the pH and also do a water change.

Bonus Advice

Research the Fish you want to buy thus, avoiding complications later on, Try your best to give them good favorable Eco-system to live in. Healthy Fish is our top priority. Look After them with utmost care. They depend upon you to give them their best environment. Have a balanced pH at the start between 6.8 to 7.8.

Author: Sunil Dcosta (


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smruti Kulkarni
smruti Kulkarni
May 24, 2022

Good information, very helpful.. Thank you.

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