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How to Balance pH Levels

| Updated September 26, 2017

Understanding pH levels doesn’t have to be hard if you remember a few things. When the pH is neutral--commonly known as 7.0--hydrogen ions and hydroxide ions are equal. Increase the hydrogen and the water becomes more acidic, leading to low pH. Increase the hydroxide ions, and the water becomes more alkaline, known as having high pH. Surprisingly, many fish can live in either as long as the pH stays balanced. Once you know a few things about how to keep it that way, you’ll be ready to start and maintain your aquarium.

Purchase an aquarium pH and alkaline test kit. This kit allows you to test the pH levels in the water, then compare it to a chart from the kit to get your pH number. Knowing the base number you are starting with enables you to ensure the pH level stays around or returns to that number when changes are made to the aquarium.

Get fish that are best suited to your water’s natural pH level. Certain types of fish prefer higher or lower pH levels--some fish, in fact, can live in water with pH as low as 5.5, while others can handle a pH level of 8.5 or higher. It is much easier to keep fish that prefer the type of water you already have instead of constantly having to adjust the pH levels.

Keep aquarium filters and gravel clean. Decaying food and fish waste can raise phosphorus levels when they accumulate. High phosphorous levels prevent your aquarium from keeping a stable pH.

Use a pH additive in the water. Many pH products on the market can increase or decrease pH levels. One disadvantage to this is that you will need to add these products each time you do a water change. Note that most of these products are better at raising pH levels than lowering them.

Consider using organic materials to naturally raise or lower the pH balance. Wood placed in the tank or peat placed in the filter system can lower the pH, while sea shells and coral can increase it. These methods will not raise or lower the pH level overnight, however, but they add buffering agents to stabilize your tank over time.


  • Do not make any sudden pH changes if the pH numbers are off. Drastically changing your pH numbers too quickly can harm or kill your fish. Slow changes to your aquarium are best.