Best pH Level for Guppies

Disclosure: When you purchase something through my affiliate links, I earn a small commission. As an Amazon Associate we earn from qualifying purchases. read more

Guppies are a popular fish breed among aquarium owners. In this article, I will show you how to care for them regarding a particular water parameter, that is none other than pH level.

First of all, you learn what the ideal pH level is for guppies. Then, we’ll see how does the pH level impact guppies in your fish tank, how to measure the pH level and what you can do to increase or decrease this level efficiently to suite your guppies.

Guppies are really hardy fish and can tolerate a range of pH level. From my experience, they do best if the pH level is kept stable at a certain level.

So, the best pH level for guppies is between 7 and 8.

This means that guppies will live best in neutral or alkaline waters. Since this is the case, you might be wondering if lower pH levels will kill your guppies. Let’s see about that!

Can Low pH Level Kill Guppies?

In most cases, guppies are quite tough, so lower pH levels won’t necessarily kill them. This is one of the reasons why guppies are recommended for beginner fish keepers. However, if you expose your guppies for such pH levels, certain health issues might occur. This is why it is recommended to always keep pH levels in check, between 6.5 and 8 at maximum.

Also, if your guppies are young, you should really keep an eye on the pH level at all times. Such guppies are more susceptible to bad water parameters, and acidic waters will affect them much more quickly. Basically, guppies won’t die from lower pH level, but to make sure they live a long life in your tank, always keep this parameter in check.

To do so, first of all you must know how to measure the pH level.

How to Measure the pH Level in Your Fish Tank?

The best and easiest method to test your water’s pH level, is to use a pH testing kit. You can get one from Amazon, and they are pretty cheap tools. How to use such a kit?

All you need to do are the following steps:

  1. Add some water from your tank in the test tube included in the kit.
  2. Next, add a drop of the testing solution in the tube as well.
  3. Finally, see how the water changes color and match this color to the corresponding color on the list, to find out what your aquarium’s pH level is.

It’s that simple! Also, you should know that most kits are designed to test water between 5 and 9 in pH level. This is where most fish species will live comfortably. To find a good product, make sure to look for one with a narrower range, that will result in more accurate readings.

However, if you don’t want to look for yourself, here’s a product I recommend. This is a digital pH meter, which will give you very accurate results and will not expire like pH strips.

Now that you know how to test the tank water, you should also know how to increase or decrease pH level in the aquarium. First, let’s talk about how you can increase the pH level:

How to Increase pH Level in Your Aquarium?

Before increasing pH levels in the tank, it is recommended to remove your fish for the time being. Next, apply the method described below. This is the simplest method, that doesn’t require any technical knowledge.

First of all, get some baking soda and measure about 1 teaspoon per 5 gallons of water. Now, according to your aquarium’s volume, add the baking soda in the tank, after you removed your guppies. Usually, this is a safe amount for easily increasing pH level, and it isn’t harmful for guppies either.

If you want to, you can first dissolve the amount of soda in some conditioned water, and add it to the aquarium like that, already dissolved. Once the pH level got to the desired level, you can place your guppies back into the aquarium.

Keep in mind one thing though: never do sudden and large increases in pH level, because your guppies will have a hard time to accommodate with the new environment. Also, health issue might surface, so be very careful about this.

How to Reduce pH Level in Your Aquarium?

Now, maybe your tank’s pH level is too high. Let’s see how you can reduce it properly:

A common method to do this, is to use peat moss. How does this work? All you need to do, is to place some peat moss in a mesh bag, then add the bag into the water filter (usually where the mechanical media sits). The used peat moss will gradually lower the pH level.

While this is happening, test the level regularly and when it hits the required level, remove the bag from your water filter. Also, using this might result in discolored water, but it passes over time. Some other methods for doing this are the following ones:

  • Add driftwood to your aquarium – it will lower the pH level in time
  • Increase CO2 levels – this works in planted aquariums
  • Decrease aeration – moderately however
  • Add RO water

Any of the above-mentioned methods will do the trick. Even so, follow strict guidelines for each process, to make sure you don’t hurt your guppies in the process.


In the end, keep in mind that the pH level in any aquarium is among the most important factors, that play a huge part in your guppies’ well-being.

Follow the steps described above, and you’ll be able to ensure a great environment for your guppies to live in.

If you have any questions, feel free to leave a comment below. I try to answer all comments as soon as possible.

Updated: March 10, 2022
Leave a Comment

Your email address will not be published. Required fields are marked *