How To Naturally Lower Your Aquarium’s pH

Maintaining your aquarium’s pH is one of the most important responsibilities as a tank owner. Acidity levels can have a huge effect on the health of your fish and aquatic plants. However, it can be difficult to lower your aquarium’s pH efficiently while keeping your fish healthy and happy. 

Luckily, we’ve compiled a list of the best ways to naturally lower your aquarium’s pH without completing altering its delicate ecosystem. With time, patience, and consistent testing you’ll be well on your way to producing a healthier environment for your fish in no time at all. 

Betta Fish In Aquarium

What is pH and the pH Scale? 

Before we get into how to naturally lower your aquarium’s pH, it’s important to have a foundational understanding of what pH is. Understanding pH and the pH scale firmly is vital to your tank’s health. 

The pH scale essentially refers to how acidic water is. Water’s acidity changes according to its concentration of opposing hydrogen and hydroxide ions. An acid will increase the level of hydrogen ions in your water, while a base will increase hydroxide ions. Pure water, which has a pH level of 7, is neutral with equal amounts of both hydrogen and hydroxide ions.

Anything that is below 7 is considered acidic, while anything above 7 on the pH scale would be considered a base, or alkalized. Therefore, when you’re working to naturally lower your aquarium’s pH, you’re essentially trying to make your water more acidic by increasing the presence of hydrogen ions.

Fortunately, you won’t have to worry about measuring ion concentrations on your own. A pH test strip should tell you exactly where you fall on the scale. Be sure to test your water’s pH before and after altering the water to see exactly how the concentration is being affected. 

What’s the Best pH Level For Aquariums?

Your aquarium’s ideal pH depends on a wide range of factors. Most importantly, you’ll need to consider what types of fish and plants you have. While most freshwater aquarium tropical fish do best at a pH of 6.8 to 7.6, it’s best to evaluate your fish on a case to case basis.

Saltwater fish are vastly different, and usually prefer a pH of above 8. Certain species of fish might even have an ideal pH level that’s uncharacteristic of their usual classification. In any event, make sure you do adequate research before acquiring new types of fish to make sure they’re compatible with your current or future aquarium environment. 

In general, it’s a good idea to focus on keeping your aquarium’s pH as consistent and stable as possible so that your fish are able to adjust to the water with some degree of predictability. 

Fish Enjoy a Natural Environment

How To Naturally Lower Your Aquarium’s pH

Without further ado, here are the best ways to naturally lower your aquarium’s pH. While investing in a reverse osmosis or auto-filtration system may be helpful for your tank, these methods can be just as effective and significantly less expensive than more automated methods. 

Be sure to try out these methods first before seeking out stronger pH maintenance solutions as you see fit. 

The Importance of Regular Maintenance and Testing 

Before getting into what you can add or take away from your tank to naturally reduce your aquarium’s pH, it’s important to stress the importance of regular maintenance and testing. While any of these methods are sure to help you raise the acidity levels of the water, nothing can substitute taking diligent care of your tanks. 

At the very least, try to test your water every two weeks to keep your pH in check. Moreover, unbalanced pH levels can be particularly stressful for young or sick fish, so make sure to test more diligently according to your tank’s current conditions. 

Some tank owners appreciate having a logbook or record so that they can dependably monitor pH levels from week to week. 

Pay special attention when introducing a new fish to an aquarium, or transferring a fish to a new tank. If you’re adding a whole host of fish to a new tank, do so gradually. When in doubt, go slow and steady— There are so many different things that can easily alter the pH of your water, so be sure to proceed with caution. 

With proper maintenance and care alone, you’ll have a good chance of maintaining your aquarium’s desired pH. 

Peat Moss 

Peat moss is an excellent way to naturally lower your aquarium’s pH level. However, you’ll need to undergo a bit of preparation process before adding this natural nutrient to your tank. You’ll want to acquire moss that is made specifically for use in fish tanks without the use of unnecessary chemicals or dyes. 

Peat moss works by reducing tannic and gallic acids into your aquarium which lowers your pH levels naturally. However, note that peat moss can discolor your water as a side effect. To reduce the amount of yellow or brown discoloration, you’ll want to pretreat your peat moss beforehand. 

Soak your peat moss in an aerated container of tap water for 3 to 4 days. Next, you’ll want to place your peat moss in a filter bag or pantyhose to ensure that it doesn’t float while in the tank. 

Make sure you add in peat moss gradually— Too much peat moss can make your water far too acidic for most fish which can be extremely detrimental to the health of your aquarium. Perform regular tests before and after adding peat moss to your tank. 

As an alternative, you could place aquarium-friendly peat moss into a separate container of tap water. When you do water changes on a regular basis, you can use this water for a more stable solution instead of putting the pretreated moss into your tank on its own. Treated peat moss can also be placed in the water filter of your tank for maintaining a healthy pH.

Once the effects of the moss begin to diminish, the old peat moss can be replaced with a fresh batch of peat moss to balance out your pH. 



Using driftwood is a great way to naturally lower your aquarium’s pH. Driftwood acts as a natural filter for your water, by taking out contaminants left behind by unwanted food or waste particles. Like peat moss, the wood releases tannic acid into your tank. 

While you can find “pet-friendly” driftwood for reptiles, this wood is sometimes treated with harsh chemicals or dyes that could be harmful to your fish. You’ll want to look for driftwood is made specifically for fish tanks without artificial dyes or preservatives. Additionally, it’s best to find a piece of wood that’s fibrous and coarse for the most efficient filtration experience. 

Driftwood can also discolor your water to a brown or yellowish color. Though this is not inherently harmful to your fish, you may want to soak your driftwood in tap water for a couple of days before placing it into your tank. 

Moreover, some recommend boiling the driftwood beforehand to properly sterilize it. Make sure that you allow the wood to cool fully before placing it into your tank. The wood should help naturally reduce your aquarium’s pH level for a couple of weeks or months. Beyond that, you’ll likely need to replace the driftwood to take advantage of its natural filtration properties. 


You can use vinegar to naturally lower your aquarium’s pH, however, you’ll want to do so while exercising appropriate caution— Too much vinegar can be extremely detrimental to certain fish, so make sure you know your species well and monitor your before and after pH levels carefully. 

That being said, vinegar does contain acetic acid which will release hydrogen ions effectively lowering your aquarium’s pH. Generally, it’s recommended that you add no more than 1mL of vinegar per 1 gallon of water. Vinegar should lower your water’s pH by about 0.2 – 0.3. Moreover, only consider using vinegar in your tanks if you have a hefty amount of plants. 

Plants naturally absorb excess carbon dioxide produced by the addition of vinegar, creating a safer environment for your fish. While using vinegar does work to naturally lower your aquarium’s pH, it should only be used in a pinch as a temporary solution. It’s recommended that you try out other options before opting to use vinegar. 

Almond or Catappa Leaves 

Indian Almond or Catappa leaves are a great way to naturally lower your aquarium’s pH. These leaves gradually decompose in water releasing helpful tannic acid (the same compound found in driftwood and peat moss). 

The leaves also work as natural filtration systems that help remove unnecessary contaminants from your tank’s water. Your fish might also appreciate these leaves as a natural hiding spot or as extra foliage in the tank. 

While these leaves can also produce a brown or yellow color change to your water, the change is much more gradual making it hardly noticeable. The color change is harmless to fish, but if it’s a concern, you can also soak the leaves on their own a day before placing them into your aquarium. 

Notably, almond leaves also have natural antibacterial properties that are great for fish in their own rite. The leaves are pretty affordable making this an excellent solution for any and all aquarium owners.

Whenever your almond leaves fully decompose, simply replace them with new, fresh leaves to continue naturally lowering your aquarium’s pH. 


Reduce Aeration 

Decreasing aeration in your tank can make it easier for your tank to naturally regulate the water’s pH levels. Aeration speeds up the process in which carbon dioxide leaves the water, which can result in a higher pH. Therefore, by reducing the speed of aeration, and thereby making it easier for carbon dioxide to stick around, your pH level is likely lowered resulting in a more acidic environment.

However, you’ll want to proceed with extreme caution here. Sudden, drastic changes can be very harsh on your plants and fish. If you choose to go this route, it’s imperative that you change your aeration levels gradually, and test regularly to monitor the alterations to your water. 

Moreover, this may not be the best route for tank owners who have otherwise experienced a relatively stable pH level— Aeration works to bring your water to its true pH level. Therefore, reducing aeration to a super stable tank is likely to have little impact if water has already clocked in at a consistent level. 

Be Cautious When Changing The Substrate 

Another way you can naturally maintain a stable pH level for your aquarium is by focusing on preventative maintenance. One of the most important things you can do is to be super cautious whenever you change the substrate or decorations of your aquarium. 

Be mindful of whenever you add something to your aquarium— However small it may be, it can affect your water’s pH. You may want to get in the habit of boiling or sterilizing any decorations you add to an aquarium, just to make sure that your fish are 100% safe. 

Make sure your tank is filled with proper gravel as well. Although it may seem like a relatively small detail, gravel can greatly affect the pH of your aquarium and therefore affect your fish and plants. 

Yellow Tang Investigates Substrate

Monitoring Your Aquarium’s pH Is Vital

The pH level of your aquarium can make or break the livelihood of your fish. Therefore, it’s your responsibility to monitor your aquarium’s pH levels diligently and adjust as needed. In addition to regular testing, keeping up with general aquarium maintenance will make it easier for your tank to maintain healthy, stable levels. 

Try to thoroughly clean your aquarium every two weeks to prevent the build-up of ammonia which can unnecessarily raise pH levels for your fish. In between cleaning your aquarium, you can perform segmented water changes using a siphon to keep your tank as fresh as possible. Also, keep a keen eye on your aquarium’s filter to ensure that it is running properly and smoothly.

Adjusting your aquarium’s pH is just one of the few responsibilities as a proud fish owner. With any of these natural pH reduction methods, you’ll be able to control your aquarium’s pH without the use of harsh chemicals or agents. By committing yourself to pH monitoring and consistent tank maintenance, you’re sure to enjoy a beautiful, healthy aquarium. 

1 Comment

  1. Like!! I blog quite often and I genuinely thank you for your information. The article has truly peaked my interest.

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