Guppy pH: Proper Monitoring Of Water Acidity For Your Pet

Guppy pH
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Last Updated: March 22, 2023 by Flora Gibbins

Did you know guppies can live up to five years in captivity? These colorful, vibrant, tropical fish live an average of three years, but they can live longer if their ideal water parameters are met. 

Great, but how?

Regarding water chemistry, you should always keep your guppies in the correct pH range. But what pH level are guppies comfortable with? And how can you maintain this pH level? 

This article discusses everything you need to know about guppy pH. 

What Is The Best pH Level For Guppies?

pH is a measurement scale for how acidic, neutral, or alkaline water is on a scale of 0 to 14. The ideal pH level for guppies is 7.0 to 8.0. These fish are hardy and can tolerate different pH levels in most pet stores. Nevertheless, it would be best to keep the pH levels in your aquarium stable, between 7.0 and 8.0. 

A pH level of 7.0 means the water is neutral. It is neither acidic nor alkaline. You can use pure or distilled water for a neutral pH. Tap water is not always neutral since it may contain treatments or chemicals. 

When the range gets to 8.0, it means that the water is slightly alkaline. Guppy fish live in slightly alkaline waters in their natural habitat and will be comfortable if you provide that. 

As previously mentioned, guppies can survive at different pH levels, including those lesser than 7. If the aquarium water is slightly acidic, it won’t necessarily kill the guppy fish. However, these water parameters can create health issues if your guppies stay in these conditions long. 

A low pH level can stress your young guppies and reduce their lifespan. Even though they will not die instantly from the acidity, their immunity and health will be impacted.

Ensure that the pH levels are constant. Fluctuating pH levels can stress a guppy, thus compromising their immunity. 

How Can You Measure pH Levels In A Fish Tank?

A pH testing kit is one of the easiest and most preferred ways to measure a guppy tank’s pH levels. You can purchase this kit online or from your local pet store. The pH testing kit may require you to dip it into collected aquarium water to change color depending on alkalinity and acidity. 

Other kits require you to collect the aquarium water in a test tube and then add a drop of two of a testing solution. The solution changes the color of the water, and you can match it to the corresponding color on the provided sheet. 

Look for a testing kit with a narrow measurement range for more accurate readings. Most kits can test pH levels between 5 and 9. However, if you get one that has a narrower range, you will get more accurate results. 

Also, test the pH levels in the afternoon. It turns out those afternoon readings are more accurate. 

We recommend you test the pH level at least once every two weeks. 

What Causes pH Levels To Drop? 

The pH level in your tank may drop due to irregular water changes and not cleaning it. This, in turn, causes ammonia spike and reduces the pH levels. Furthermore, if you do not test new water when adding it to the aquarium, it can also cause the pH to drop. 

How Can You Increase pH Level For Guppies?

If the testing kit shows that your tank pH is lower than 7, you must raise it. You can achieve that in one of the following ways:

1. Add Baking Soda

Add Baking Soda

You can increase the pH level in a tank using baking soda. However, you need to remove your guppies from the fish tank during this procedure. Next, do the following steps. 

Step 1: Measure 1 teaspoonful of baking soda for every 5 gallons of water. This is a safe amount for guppy fish.

Step 2: Dissolve the baking soda in conditioned water depending on your tank size. If you own a 20-gallon aquarium, you will need 4 tablespoons of baking soda. 

Step 3: Add the dissolved solution into the fish tank. 

Step 4: Let the solution sit for 30 to 60 minutes. 

Step 5: Add your guppies back to the tank. 

While increasing the guppy pH, make sure you do not make sudden increments. For instance, if your tank water has a pH of 6.5, increase the pH level gradually to a 6.8 or 7.0. 

Follow the steps mentioned above and it will help your guppy fish transition easily into the new environment. 

Watch this YouTube video on how to raise the pH level:

2. Add Aerating Decorations

Add Aerating Decorations

Aerating decorations promote air circulation by producing bubbles. This is a win for you since they not only decorate the tank but also stabilize the pH level. However, they take up a lot of space. 

3. Use Macro Algae

Use Macro Algae

Macro algae are efficient algae that grow to form a natural seabed. In addition to increasing the pH level, the algae provide hiding spots for your guppies. 

4. Use Dolomite Chips

Dolomite Chips

Dolomite chips have high calcium and magnesium levels that can raise the pH level.  They create an ideal environment for guppies while making your aquarium beautiful. 

Other methods to raise the pH level for guppies are:

  • Frequent water changes to stabilize pH level.
  • Clean and boil tank decorations to remove bacteria and prevent pH imbalance.
  • Add crushed coral as substrate.

What Causes A Rise In pH Levels?

Chemicals and gas exchange are the main factors that raise pH levels. Chemicals are pollutants present in the aquarium that spike over time. On the other hand, gas exchange refers to the CO2 and oxygen cycle. The levels increase when CO2 leaves the tank and into the air. 

How Can You Reduce pH Level In A Guppy Tank?

If for some reason, your aquarium has high levels of pH, you must reduce it. What’s comforting is you do not necessarily need chemicals to do it. You can lower the pH level by:

1. Using Peat Moss

Peat Moss

Peat moss is the most common way to lower the pH level. The process is straightforward since you put peat moss in a mesh bag and then introduce it to the water filter. You may observe discolored water for some time, but the peat moss will gradually lower the pH. Remove the mesh bag once you achieve the desired level. 

2. Adding Driftwood

Adding Driftwood

You can also add natural driftwood to your aquarium. Driftwood releases tannins that lower the pH level. 

3. Using Catappa Leaves

Using Catappa Leaves

Like driftwood, Catappa leaves also release tannins to reduce pH levels. These leaves may turn the aquarium water yellow, but they do not hurt fish. Moreover, they are antibacterial and antifungal. 

4. Injecting CO2

Injecting CO2

If your guppy tank is heavily planted, you can inject CO2 to lower pH. Unfortunately, many aquarists find this method challenging. 

Fun Fact: Read our interesting post on How To Add Carbon Dioxide To Aquarium In 4 Easy Methods for a fuller explanation of the process presented above.

5. Adding Substrate

Adding Substrate

Rocks and substrate can help replicate a guppy’s natural habitat. Moreover, they help stabilize pH levels. However, do not add sharp-edged rocks as they may tear your guppy’s fins. 

6. Adding Reverse Osmosis Water

Reverse Osmosis Water

Alternatively, add deionized water or reverse osmosis water during water changes to provide buffering. Test to confirm that the pH levels are ideal. 

7. Using Chemicals

Using Chemicals

Some chemicals help neutralize the chemicals present in tap water to reduce pH levels. 

Watch This!

Frequently Asked Questions

What Are The Effects Of High pH Levels On Guppy Fish? 

Guppies can tolerate high pH levels but to a degree. If it is too high, it creates an unhealthy alkaline environment with the wrong water chemistry. This makes the fish prone to developing health problems and shortens their life. 

What Are The Effects Of Low pH Levels On Guppy Fish?

Low pH levels won’t kill your guppies immediately. But it will affect their lifespan in the long run. Acidic water will become toxic for your fish and stress them out. 

What Is The Best Water Hardness For Guppies?

Water hardness should be between 8 to 12 dGH. Remember to maintain this water parameter as it is also crucial.


The best pH level for guppies should be 7.0 to 8.0. Maintaining this guppy pH will allow your pets to live happily, healthily, and for long.

If the aquarium water becomes too acidic or alkaline, your guppies will not die instantly, but they will get stressed and fall sick. Fortunately, you can avoid this by raising or lowering the pH level. 

Always test the pH level once weekly to ensure the water parameters are perfect for your guppies. 

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