The Best pH Level for Guppies

Because guppies are such a popular fish species for many who own a freshwater aquarium, it is good to know how best to care for them. While they are generally fairly easy to care for and maintain, one matter which a potential owner should educate himself on is the best pH level for guppies.

Best pH Level for Guppies

Guppy fish are a fairly hardy species of fish which can actually tolerate a range of pH levels. However, they will definitely fare better if you are able to keep the pH level of the water stable, at a particular level.

So what is the ideal pH level for guppies? The best pH level is 7 to 8 for your guppies. A pH of 7 denotes completely neutral water (such as pure or distilled water) with no acidity or alkalinity. Anything lower than a pH of 7 is acidic, and anything higher than 7 is basic or alkaline. A pH range of 7 to 8 means that guppy fish will thrive in waters which are neutral or slightly alkaline.

Be aware of the fact that because guppies are fairly hardy and tough, a water tank with a pH of lower than 7 will not necessarily kill your guppies. In fact, their hardiness and toughness makes them an easy and popular recommendation for those who are just beginners in terms of fish keeping.

However, if guppies are kept in water with a pH of less than 7 for prolonged periods of time, there are some health issues that may arise. Thus, it is important to try to maintain optimal pH levels for your guppies. At the very least, you should keep the pH level above 6.5 and below 8.

Furthermore, guppies which are still young and not yet mature will be much more affected by the wrong water parameters, and water that has a pH below 7 will have an effect on these young guppies much faster. They probably will not die from a pH level that is on the lower side, but in order to increase their longevity and protect their health, you should always check on this water parameter.

How to Measure the pH Level in Your Fish Tank

The easiest way (which also happens to be the best way) to test the pH level of your water is to test it with a pH testing kit. Such testing kits are readily available from Amazon and come fairly cheap. Here are general instructions on using these kits (specific constructions will likely be included with the kit itself; when in doubt, you can refer to those):

Step 1: Add water from the fish tank into the test tube that comes with the kit.

Step 2: Add one drop of the solution for testing into the test tube that contains the water from your fish tank.

Step 3: The water will change color; match the color of the water to the corresponding color on the sheet or list provided by the kit in order to determine the pH level of your aquarium.

That’s all. Another tip is that many pH kits have been designed for testing water with a pH level from 5 to 9. To get more accurate results, you can look for a testing kit that focuses on a narrower range. This will get you a pH level reading that is more accurate.

How to Increase pH Level in Your Aquarium

After determining the pH level of the water in your aquarium, if you find that the pH level is too low, you will need to increase it in order to protect the health of your guppies. Before you increase your tank’s pH levels, you should remove your guppies from the aquarium temporarily. Then take the following steps, which will require baking soda:

Step 1: Measure out approximately 1 teaspoon of baking soda for every 5 gallons of water in the tank. This is generally a safe amount of baking soda for increasing the pH level of your tank, and it will not do any harm to your guppies.

Step 2: Add the measured baking soda into your tank (be sure that you have already removed the fish).

You may wish to dissolve the baking soda beforehand in conditioned water. You can then add the already dissolved baking soda into the tank. After you reach the desired pH level for your water tank, place the guppy fish back into your tank.

You should never create large and sudden increases in the pH level because the guppy fish will have some difficulty adjusting to that new environment, and health issues may surface as a result.

How to Reduce pH Level in Your Aquarium

If the pH level in your aquarium is too high, you can reduce it in the following manner:

Step 1: Acquire peat moss and place it into a mash bag.

Step 2: Add that bag into your tank’s water filter. The peat moss will lower the pH level gradually. The water may be discolored by this process, but it will pass after a period of time.

Step 3: Next, test the pH level regularly. When it falls to the desired level, take the bag out of the filter.

The peat moss method is a common one. Other methods include adding driftwood into the tank, which lowers the pH level over time, moderately decreasing aeration, increasing CO2 levels (which works well in planted aquaria), and adding reverse osmosis (RO) water.

Be sure to follow guidelines strictly no matter which method you use and test the pH regularly to ensure that the health of your guppies is safeguarded.


Since the pH level of your aquarium is a determining factor in the health and longevity of your guppy fish, it is important to check it and maintain it properly to preserve the well-being of your guppies. By taking the above steps in this article, you can provide an environment in which your guppies may live healthily and happily.

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