How to lower pH in Freshwater Aquarium? Tips To Maintain Ideal pH Level

Learn how to lower pH in freshwater aquarium to help maintain a good lifespan of the fishes and avoid death after changing the water.

A freshwater aquarium is the best place to keep the fishes in to showcase its beauty. But the pH level of such an aquarium can be hard to maintain. It can change and get higher after some time, or even if you change the water of the aquarium.

How to lower pH in Freshwater Aquarium

The pH level can be the #1 threat to the fishes. If you don’t check and fix it, the fishes might die inside the aquarium.

To help you fix it, let’s go over a few methods on how to lower pH in freshwater aquarium that you can use if the pH level gets high. 

Ideal pH Level

Before you move on learning lowering the pH level, you must know what’s the ideal pH level for the aquarium water. It’s going to have the biggest impact on the welfare of the fishes inside the water tank. 


The pH of water ranges from 0 to 14, and different breeds of fishes have a completely different need for pH levels. However, the basic rule of thumb here is that anything lower than a 7 indicates that the water is acidic. 7 is right in the middle and it’s the neutral pH level of the water. And anything above 8 is alkaline.

You should have a pH level of 5.5-7.5 if you are dealing with freshwater aquariums. If it gets higher than that, you may consider using the following methods.

how to lower ph in freshwater aquarium
how to lower ph in freshwater aquarium

(1) Changing the Water Regularly

The #1 reason for the pH level to rise is that you don’t change it often. It’s one of the fastest and the most effective way to lower the pH level in a freshwater aquarium as well. It helps to remove all the excess food and fish waste from the water, making it better.

However, if you know how to save dying fish after water change, you can probably tell that it’s not the best idea to rush the whole thing. Be slow, and only change 40 to 60 percent of the water. That should be enough to lower the pH level significantly.

This is a perfect time to clean the gravel and decoration as well to reduce the alkaline stage. Changing the water in your freshwater aquarium is the best way to keep the pH level balanced.

(2) Replace the Filter

Sometimes the pH level of your aquarium water is going to get high if you don’t change the filter on time. A filter is one of the most important components of an aquarium that keeps the debris and bacteria away, which helps to maintain a balanced pH level in the water.

You should get a water filter online or at your nearest pet store. But you don’t need to replace it if it’s working fine and needs a bit of cleaning. For that, you can take it and rinse it using clean water. Be sure not to use any chemical, and don’t take the sludge off of the filter. That’s a pretty effective method on how to lower pH in freshwater tank, and you should definitely be mindful of the state of the filter.

(3) Add Peat Moss

One of the most common ways to reduce the pH level of your freshwater aquarium is by adding peat moss in there. Add it directly to the filter or anywhere in the tank, and it’s going to do wonders and take the pH level down naturally. 

However, you should avoid putting it directly on the water as it can be a bit harmful to the fishes. Try submerging the peat moss in a container for a couple of days, and then you can use it without any issue. Yet, it can turn the interior a bit yellowish, and this is where learning how to keep fish tank clean without changing water can come in handy.

(4) Using Driftwood

Driftwood is another method of lowering the pH level of the water naturally. It releases tannins into the water, which drastically improves the pH level and lowers it down. 

First, grab some driftwood online or from your local pet store. You can put it directly into the water, but the color produced from it can mess up the look of your freshwater aquarium. You should boil it in salt water before you apply it, and that way it won’t be too messy. If you are not sure how to lower pH in aquarium, this is a great method to use.

(5) Reverse Osmosis

The final method that we are going to talk about is reverse osmosis. If you own a smaller sized aquarium, this is not the best option for you. The filters used in this method are pretty big and bulky in size, and you’d have to replace it quite regularly. That is pretty expensive as well.

However, it is a great long term option that you can have for your aquarium. It’ll help to maintain a stable pH level in the aquarium, and the fishes are going to be happy with the water despite its main source. It doesn’t produce any color like previously mentioned methods, and it kills all the germs and bacterias, which helps to enhance the lifespan of the fishes as well. So, if you can afford it, you should get it. It’s well worth your money, and it’s actually the best solution that you can have for balancing the pH level of your aquarium.

Final Thoughts

These were some methods on how to lower pH in freshwater aquarium, which is pretty effective. Make sure to use a few of these as soon as identifying a higher pH level than the ideal. That’s going to help save a lot of fishes inside your water tank.

Also, be sure to only use the chemicals that are not harsh on the fishes. That can have the opposite effect that you definitely want to avoid. Try to go with a natural method first, and then you can move on to using chemicals if you don’t see any results.

Writer: Shyran Khan Joy

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