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Raising pH in an aquarium

Fish survive and thrive based on their environment. A core component of this environment is the pH level. Optimum pH levels for health and well-being depend on whether your tank carries tropical or freshwater fish. The good news is that most fish are highly adaptable. The bad news is that if the pH of your tank is exceptionally low, it may not only stress your fish, but it could be fatal.

What is low pH in an aquarium?

The pH in your aquarium is a representation of acidity or alkalinity. A neutral pH is 7. An acidic pH level is anything below 7 down to 1. Therefore, if you need to raise your pH in your aquarium, it’s more often than not because the water has become acidic.

Why is pH important for your aquarium?

If your fish are sick or young, significant variations in pH can be catastrophic. What’s more, if you aim to breed fish in your aquarium, pH is a significant factor in successful breeding of healthy eggs. Tracking and adjusting pH when cleaning aquariums is incredibly important to reduce the shock and stress on fish during the process.

Not only that, but an incorrect pH level can have a serious impact on the mood and even the appearance of your fish. There can be a lot of work associated with owning an aquarium, such as the cleaning, but it all goes toward maintaining a happy and healthy tank of fish.

What pH level should your aquarium have?


The correct pH level for your fish depends on the diversity of your aquarium. This means that no pH is normal and will vary from tank to tank. Typically, freshwater fish exist in a range of 6.8-8.0. However, tropical fish tend to operate in neutral pH, which is typically around 7.

If you’re unsure whether your tank water is at the right pH level for your fish, try visiting a specialist pet store. Make sure you know the breeds of fish you have in your aquarium and use a water testing kit beforehand so you can explain the situation. They should be able to tell you whether pH is the issue and what else you should be looking at if it’s not.

How to check the pH level of your aquarium

pH logbook

Check pH levels at least once per month. However, if you have a particularly variable tank or a large number of fish, aim to check pH levels every two weeks. Using a pH logbook can help you identify patterns and trends over a broad period and give you data to notice trends and act accordingly.

Ways to raise the pH in an aquarium

Air and water pumps

Air and water pump

An air and water pump can decrease the volume of carbon dioxide by increasing the amount of oxygen in aquarium water to raise the tank’s pH level. Using a filter at the water’s surface disturbs the flow and in doing so, aids the movement of oxygen around the water.

If you opt to use a log to track the changes in pH, you will identify whether or not the pH level is at an optimal level. Moreover, it lets you know if ornaments or plants are raising the pH level in the tank.

For more on the best air pump to buy for your aquarium, check out the full buying guide from Best Reviews.

Coral rock

Coral rock can quickly raise the alkalinity of freshwater tanks and sustain pH 7.8. This increased pH stability means the overall ecosystem of the aquarium remains stable and healthy even during water changes, given that the pH stabilizer comes from the coral.

Most commercial coral options you can use in aquariums do not contain phosphates, so they don’t cause algae growth. At the same time, coral rock boosts the alkalinity properties and stabilizes freshwater aquariums and planted ones. If you don’t have access to coral, you can use alternatives such as limestone or petrified coral.

Chemical pH adjusters

Chemical options are best for owners who test pH levels weekly to adjust the tank to an optimal pH level. Chemical options neutralize the acidity in the water. Most options do not promote algae growth, and if managed weekly, pH adjustments should be safe for plants. The best options typically are phosphate-free and have a reasonably long shelf life even when used weekly.

What you need to buy to raise pH in an aquarium

API pH Freshwater Aquarium Test Kit

API pH Freshwater Aquarium Test Kit

This kit contains 250 tests for weekly testing of the pH levels in freshwater aquarium tanks. It’s simple to use, highly accurate and can help you to detect fluctuations in the pH level.

Where to buy: Sold by Amazon, Petsmart and Chewy


Kordon pH Increase Adjuster for Aquariums

Kordon pH Increase Adjuster for Aquariums

This pH increaser can be used in both freshwater and saltwater tanks to increase the alkalinity of the water. Just make sure to prepare the new water with the increaser first, prior to a cleaning, to keep your fish safe.

Where to buy: Sold by Amazon

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Lauren Farrell writes for BestReviews. BestReviews has helped millions of consumers simplify their purchasing decisions, saving them time and money.

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