What Causes PH Changes and How to Fix Them

What’s the chemistry like between your aquarium fish and the water they swim in? Keeping the pH of your tank water is a vital element when it comes to keeping your fish healthy.

In order to keep your aquarium fish happy and healthy you need to maintain high water quality in your tank. Having a filtration system in place and performing weekly water changes will go a long way toward preserving water quality, but you also have to think about various aspects of water chemistry. The pH level in your tank is important and it may change from time to time – when it does, you need to know what you can do to get it back to normal.

Causes of Change in pH

The pH of your tank water is a measure of the alkalinity or acidity and it is measured on a scale from 0 to 14. A neutral pH is measured at 7.0. Any measurement below 7.0 is said to be acidic while pH values above 7.0 are alkaline. There are a number of factors that contribute to the pH level in your tank including the trace mineral content, the type of substrate you use, and the chemical concentration in your tank water. If any of these things changes, it could lead to a change in the pH value of your tank water. Other things that might cause a change in pH include the use of certain medications, the failure of your filtration system, or even certain objects or decorations in your tank (like driftwood). The key to dealing with changes in pH is to identify the cause.

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Tips for restoring pH in the Aquarium

The pH in your aquarium can go one of two ways – up or down. If the pH in your tank suddenly drops, there are several things you can try to raise it:

  • Perform a water change. If you don’t keep up with regular water changes in your tank, the chemical balance will change and that will affect the pH. Performing a water change will help to restore the natural pH level of your tank water.
  • Changing your substrate. Certain types of substrate will naturally raise the pH in your tank. Things like crushed coral or limestone have this effect but keep in mind that it will be hard to control the degree to which these substrates impact your pH.
  • Increase the aeration in your tank. When you increase the oxygen levels in your tank water you will be decreasing the carbon dioxide levels and that will increase the pH. Adding an airstone to your tank or installing a more powerful filter can have these effects.
  • Using baking soda. If you need to change the pH of your tank water, adding baking soda may help. It is important that you don’t add too much at once, however, because sudden changes in pH can be deadly for your fish. Do not add more than 1 teaspoon per 5 gallons and make sure it is thoroughly dissolved in water before you add it to the tank.

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These are just a few of the ways you can increase the pH in your tank. If you need to lower the pH in your aquarium, try one of these methods:

  • Add peat moss. Using peat moss as the substrate in your tank or simply adding some to your filter may help to lower the pH in your tank – just be sure not to lower it too much at one time.
  • Increase carbon dioxide. As you already learned, low levels of carbon dioxide frequently correlate with higher pH levels. You can expect the opposite to be true as well. To help lower pH in your tank, increase CO2 levels by reducing aeration or by adding supplemental CO2.
  • Add driftwood to your tank. Driftwood contains tannins which not only stain your tank water brown, but also lower your water pH. Just be careful about how you use it.

Maintaining proper water chemistry in your aquarium is a balancing act. By testing your tank water on a weekly basis you can establish a baseline for the “normal” water chemistry of your tank. Then, if you get a test result outside the normal range, you will know that something is wrong and you can take steps to fix it. Just be sure not to make any sudden changes to the water chemistry in your tank because your fish might not be able to handle it.

Kate Barrington
Kate Barrington

Kate Barrington is the loving owner of two cats (Bagel and Munchkin) and a noisy herd of guinea pigs. Having grown up with golden retrievers, Kate has a great deal of experience with dogs but labels herself a lover of all pets. Having received a Bachelor's degree in English, Kate has combined her love for pets and her passion for writing to create her own freelance writing business, specializing in the pet niche.

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