How To Lower Ph In Aquarium? All You Need To Know

The pH level, which regulates how acidic or alkaline the liquid can be, is an essential factor for the survivability of the fish in your Aquarium. Not understanding how to lower pH in the Aquarium and the reason for doing that in the first place? Well, read along, and we will be revealing everything to you. To ensure that your fishes in the Aquarium get enough oxygen and don’t get afflicted with diseases, you need to know the techniques by which you can lower the pH. 

Obviously, you don’t want your pretty fishes to die because of the improper pH level in the fish tank, right? Sadly, the Aquarium’s pH level often exceeds normal in the fish tanks, which is why you need to apply methods that contribute towards lowering the pH level of the aquarium water. 

You can easily understand if the current pH level of the aquarium water is suiting the fishs’ health by keeping a close watch on their behavior. Check if they are showing any signs of distress or discomfort in the fish tank. If yes, the first thing that you need to check is whether the pH level of the water has exceeded the usual level. 

Are you getting puzzled about how you can measure the pH level of the water and bring the level back to normalcy? If yes, don’t stress out! After all, we will help you out in lowering the pH level of your gorgeous fish tank so that all the fishes and the aquarium plants thrive in a healthy condition. 

Gear up to delve deep into the world of water chemistry! Come on, let’s begin with the main discussion now. 

What is pH?

Scratching your head a bit may take you back to those 6th or 7th-grade chemistry classes in which your tutor used to discuss pH. As students, we all have learned about it in the past.

But, some of us may not remember about it at the same time, right? Well, so let’s see what exactly pH is!

how to lower ph in aquarium
Man determining water pH by comparing the color of the liquid in a testing vial with the attached color scale. Water is alkaline

To explain in short, pH is the measurement of how acidic or alkaline a liquid is. As we all know, water or H2O is composed of molecules of hydrogen and oxygen.

When these molecules get split up in small amounts in the water, some of these do away with hydrogen and evolve into hydroxide ions or OH-. Water, free from any impurities, consists of an equal number of both hydrogen and hydroxide ions.

Just when any impurities or acidic/alkaline substance gets dissolved into the water, the balance of the ions gets altered dramatically. Thus, it results in a change in the pH of the water. 

But, what is the difference in the water getting acidic or alkaline? When the water becomes acidic, the number of hydrogen ions increases, and the pH level reduces.

When an alkaline substance gets mixed with the water, the hydroxide ions increase, thus leading the pH level to increase. 

An aquarium needs to have neither too high a pH level or too alkaline nor too low a pH level or too acidic. The condition has to be such that the health condition of the fishes and plants is maintained.

What is The pH Scale?

Before knowing how to lower pH in the Aquarium, it is essential to understand what a pH scale is. A pH scale is a tool that is used for measuring the acidity or alkalinity of water. It is measured on a scale having graduations from 0 to 14.

The pH level of 7.0 is marked as neutral. If the water has a pH value below 7.0, it is acidic. However, if the pH value of the water is above 7.0, it is alkaline or basic. 

pH scale
pH value scale chart for acid and alkaline solutions, acid-base balance infographic, vector illustration

Each fish species had different requirements. While a fish of a particular species will survive well in a slightly acidic environment, the other may find it comfortable to dwell in alkaline water.

You must maintain the pH level in the fish tank as per the needs of your fish. Else, they might fall sick and eventually die from being compelled to live either in a too acidic or too alkaline environment. 

As a result, if the pH level of the water is too high, you need to know how to lower pH in the Aquarium and vice-versa.

When is it Necessary to Lower the pH in Aquariums?

Lowering the pH in aquariums becomes necessary for ensuring the maintenance of the health of the fish that have been added to the fish tanks.

Since the fishes belong to various species and come from varied countries worldwide, they have their own water quality requirements. 


If your Aquarium consists of fishes hailing from the tropical and equatorial regions of Southeast Asia or South America, such as tetras, angelfish, or barbs, know that they survive well in acidic waters.

The captive-bred aquarium fishes don’t have any such specific requirement about the water pH level. However, adhering to the proper pH level is a good idea to ensure that their health is maintained correctly.

Ensure that the fish tank water is more alkaline if you have kept African cichlids and reef fishes in the Aquarium. 

All you have to do is gain proper knowledge of the requirements and survival parameters of the fish that you wish to introduce in your Aquarium. In that way, you will come to know about the correct water parameters in which your dear fishes will be able to survive. 

Tools to Monitor the pH in Your Aquarium

Let’s now look at the tools or strips that you can use to regulate the pH in your Aquarium and ensure the proper health of your fish. 

An aquarium
Man feeding fishes in the aquarium.

API’s Pond Testing 

API’s Pond Testing is a reagent-based drip kit that is used to test the pH of water. Add water to the tube and then test it with the reagent to carefully notice the color change in the water.

Keep a pH scale chart with you as it contains varied shades of color and the mentioned degree of acidity or alkalinity. Look at the color in the chart and see if it matches with the color result that you have got to get the pH level of the water. 

Dip Test Strips 

All you have to do with a dip test strip is to dip the strip into the aquarium water and compare the obtained results with a well-illustrated color table.

This test will probably take you 1-minute maximum. You can even use the dip test strips to test the presence of kH, pH, ammonia, iron, etc. 

Digital Meters 

The digital pH meters can show the result down to 0.001 by using color charts for better accuracy. 

Frequency To Test pH In An Aquarium

So, now this question of the frequency of lowering pH in your Aquarium is lingering in your mind, right? Well, we are here to answer it!

An aquarium
Family cleaning reef tank. Father standing next to a reef tank and helping son with hose

Ensure to have a look at the pH level of the fish tank at least once every one month or four weeks. In that way, you will quickly notice the changes that have occurred in the fish tank.

It is better to note down the pH levels of the aquarium water every time you check it in a notebook.

Since the pH level tends to vary at different times of the day, it is advisable that you test the pH level only at a particular time of the day every time, say, during the afternoon. 

It is an excellent practice to check the pH level of the water in the Aquarium every time any of the fish dies or falls ill.

In fact, even before you introduce any new fish to the Aquarium, make sure to check the pH level of the fish tank. Try to keep the Aquarium as clean as possible so that the proper pH balance is maintained. 

Make it a point to replace at least 10 to 20% of the aquarium water with fresh water. Dechlorination of water is essential before doing the replacement if the freshwater has chlorine in it. Filters and siphons can also be used to clean the fish tank.

The presence of dirt accelerates the pH level of the water. As a result, keeping the tank clean is essential for maintaining the proper pH in the Aquarium. 

How To Lower pH Levels in Aquarium Naturally?

Fishes in an aquarium
Two goldfish swimming right to left, with red and white stones at bottom and green plant in the background

Lowering the pH level in your Aquarium by using natural items such as peat moss, almond leaves, and driftwood is a good idea.

In fact, as a natural method of lowering the aquarium water pH, you can also use an Osmosis filter because no chemical is used in this testing method. Remember that keeping your fish tank clean and removing any impurities is essential in keeping the pH level under control. 

Let’s now see how you can add these natural items to lower the pH level of the water in your Aquarium. 

By Using Driftwood 

Driftwood over white background

You can add either 1 or 2 pieces of driftwood to your Aquarium and witness it working as a solid filter to eliminate the fish tank’s impurities.

Since driftwood doesn’t come with any artificial dyes or chemicals, it is absolutely a good item that you can use to maintain the health of the fish. 

Make it a point to boil the driftwood before adding it to the Aquarium. Else, it would lead to the coloration of the water in the fish tank. You may choose not to boil the driftwood before adding it to the tank.

But, in that case, you need to ensure that you are letting the driftwood soak in pure, clean water for ten days before adding it to the Aquarium. 

Driftwood is an excellent option to regulate the pH level in your fish tank. You can even keep it inside the Aquarium for several months and even years. This will perfectly act as a natural filter for your fish tank without you having to worry about a thing. 

By Using Almond Leaves 

Almond leaves come with several benefits, so using these may work wonders for the health of your aquatic creatures dwelling in the tank.

Almond leaves
Almonds on white background

Apart from lowering the pH level of the water naturally, almond leaves also help safeguard the health of the fish because these contain vital anti-inflammatory ingredients. 

Moreover, these leaves have an aesthetic quality and add to the splendor of the Aquarium. Do you know what another good thing about almond leaves is? These give the fish a natural spot to hide and play around in the Aquarium. 

You can get the best quality almond leaves from any good local pet store. Ensure to soak these leaves inside clean and pure water for about 24 hours before placing these in the Aquarium.

This will aid in the removal of tannins which would have made the aquarium water turn yellow. That is why you must soak the almond leaves in freshwater before adding these to the fish tank. 

After 24 hours of the leaves being soaked, spread these at the floor or bottom of the fish tank. You must keep changing the almond leaves every six months. Else, these would look ragged and torn. 

By Using Peat Moss 

You will get natural peat moss from any local pet store. However, at the time of purchasing, always check if you are buying completely organic peat moss that can be used ideally in the fish tanks.

Peat moss
Green moss on white background

Don’t add the peat moss into the fish tank right after purchasing, for it may turn the aquarium water a bit brownish or yellowish. That is why it is essential that you soak the peat moss in pure water for four days. Only after four days can you add the peat moss to the fish tank. 

To ensure that the pH of the water gets lowered slowly and not drastically, place the peat moss in small amounts in a filter bag. Place this peat moss-containing bag in the Aquarium to ensure that the natural moss doesn’t float on water.

Keep changing the peat moss every six months or anytime when you notice that it has grown old and tarnished completely. 

By Using Reverse Osmosis Filter 

RO Filter

A Reverse Osmosis (RO) Filter does not make use of any chemical, so it is also a realistic option to bring down the level of the pH of the water in your fish tank.

It purifies the tank water by using a semi-permeable membrane to trap the impurities, heavy metals, or ions. You can get these from any offline or online store at a price varying from $200 to $400. 

A RO filter is instrumental in lowering the pH of the fish tank and maintaining it at a proper level.

But, how many filtration stages RO units should you purchase? Well, if you have a small fish tank, a RO unit with two filtration stages will work effectively.

If your Aquarium is moderately giant, go for the three filtrations stages-RO unit. Purchase the four filtrations stages-RO unit if you own a super large aquarium. 

You may call for the help of a professional or may set up the filter by yourself with the help of the instruction manual. 

By Cleaning The Aquarium Periodically 

Periodical cleaning of the Aquarium is essential to lower the pH level of the water in the fish tank. Spare a little time from your schedule to clean the fish tank every two weeks.

Cleaning the Aquarium is essential in removing the layer of ammonia that builds up in the water, and thus the pH level will be reduced to a great extent.

First of all, remove the algae from the tank. Now, replace about 10 to 15% of the tank water with dechlorinated water from the tap. 

Cleaning an aquarium
Aquarist and aquarium сare. Home aquarium cleaning process.

Use a siphon to remove about 25 to 33% of the gravel from the Aquarium. You may also use a protein skimmer to get rid of other impurities from the fish tank. Perform a trial to see if the filter is working correctly.

Make sure to change the water at regular intervals, say once a day or once every 5 or 6 days. While doing so, aim to replace at least 30% of the tank water. 

After you maintain a constant streak of cleaning the Aquarium, test the pH level of the water and see if it stays at a stabilized level. Make sure to stick to a pH level that matches the requirements of the fish that you have added to the tank.

Every time you modify the aquarium environment or add any new fish or plant to it, checking the pH level is necessary. 

Techniques To Lower Ph In Aquarium With Vinegar 

An aquarium
A middle-aged Asian man feeds the guppy he raises in a small fishbowl.

We will now look at the steps by which you can lower the pH in aquariums with vinegar. 

  • First of all, test the freshwater of the Aquarium only after allowing it to settle down for a duration of 12 to 18 hours. 
  • Add white vinegar drops to the water that you have taken as a sample. 
  • Now, take the pH test strips to check the pH level of the water. Pay proper attention to the color changes to know what is the current pH level of the water. 
  • It is recommended that you use 10 ml of white vinegar for every 10 gallons of water in the fish tank. 
  • Always remember not to add the vinegar directly in the tank water. This is because an instant and sudden drop in the pH level of the water won’t be conducive for the health of the fish and aquatic plants. 

Do note that the prescribed amount of vinegar may change for your tank depending upon insecticides, pesticides, heavy metals, or carbonates present in the water. That is why it is better first to test the water and then try using vinegar to lower the pH in your Aquarium. 

How Much Vinegar To Lower Ph In Aquarium?

Are you pondering how to lower pH in Aquarium quickly with vinegar and what amount of vinegar you should take? Well, the process of using vinegar to lower the pH level is mentioned above.

white vinegar on the wooden table

Note that the amount of vinegar you need to use depends upon the concentration of minerals, heavy metals, ions, and carbonates present in the water. For every 10 gallons of fish tank, you can take 10 ml of white vinegar.

However, this amount may vary depending upon the mineral content of the water present in your fish tank.

How To Lower Ph And Hardness In Aquarium? 

Goldfish in a night illuminated aquarium

Now that you know how to lower pH in aquariums, let’s see how the hardness in an aquarium can be reduced and be made softer.

  1. You can use driftwood to reduce the hardness of the water in your Aquarium. Yes, you have got that right! Driftwood is such a substance that can lower both the pH and the kH of the water in the fish tank. After purchasing it from a local store, soak it in water for a certain period so that the tannins get dissolved in it. Later, add the driftwood into the fish tank to witness the reduction in the hardness of the water.
  2. Using rainwater in the Aquarium is a great idea to keep your fish in soft water. However, rainwater is way too soft by nature, so you may have to mix it with tap water and other essential aquarium salts to ensure that the water doesn’t get too hard or too soft.
  3. Water softening pillow(s) is another excellent item that you may add to the Aquarium to reduce the hardness of the water. These softening pillows act as a filtration media that decreases the calcium and magnesium levels and enhances the sodium levels of the water. These can be used ideally in smaller aquariums. But, that doesn’t mean that you cannot use these in a large aquarium. It would help if you recharged these more frequently to ensure that the water doesn’t get too hard. Be a bit careful while using these as the sodium level of the water increases and may affect the health of the fish.
  4. You may also use a RO Filter as it helps remove the minerals from the water by making it undergo the passage via a semi-permeable membrane at tremendous pressure. In this way, the water in the Aquarium will get softened to a great extent.
  5. Peat Moss is another excellent item that you can use to soften the aquarium water. It reduces the carbonate levels and the pH of the water and also softens the water. Before adding it to the tank, ensure that it is well aerated and proper oxygen levels are maintained inside it. Just sterilize or boil the peat moss before adding it to the Aquarium so that the water in it doesn’t get colored and turn brown.

How Much Peat Moss To Lower Ph In Aquarium? 

While lowering pH in an aquarium with peat moss, make sure to use only the organic one. Use only a handful of it, and place it in a filter bag to ensure that it floats in the tank water.

Avoid adding a considerable amount of peat moss to the fish tank. Else the fish may suffer from sudden pH shock.

How To Safely Lower Ph In Aquarium?

An aquarium
Aquarium Plant Tank Designe Aquascape

Wondering how to safely lower pH in your Aquarium? Well, you can try the following methods.

By Adding Carbon Dioxide

Infusing carbon dioxide into the water lowers the pH level of the water to a great extent. So, you can add carbon dioxide into the tank to safely decrease the pH level of your Aquarium.

By Using Chemicals

Though using chemicals to lower the pH is not suggested, you can try this process occasionally to decrease the pH level in the fish tank.

This process of using chemical items to lower pH in the Aquarium is not recommended because you have to keep repeating this treatment as it fetches only temporary results.

That is why it is better if you use the natural ways of lowering the pH, that is, by adding catappa or almond leaves, peat moss, driftwood, or using RO, that is, Reverse Osmosis filter.

Conclusion: How To Lower pH In Aquarium

Well, so that was all about “How to Lower pH in Aquarium!” Hopefully, you will now be able to quickly lower the pH in your Aquarium and create a safe living environment for your beautiful fishes.

The processes mentioned above are elementary to apply, so start applying any of these methods, and you will get the result. Keep a pH scale or test kit handy to check the pH level. And, it will be done! Good Luck!


Will Plants Lower pH in an Aquarium?

It cannot be said with certainty if plants lower pH in an aquarium. Depending upon the type of plant you add to the Aquarium, the pH level in the fish tank can be either increased or decreased. The water may get acidic if the pH level lowers, or it may turn alkaline if it increases.

Natural Ways to Lower pH in Your Fish Tank

The most notable natural way by which you can lower pH in your fish tank is by adding driftwood, peat moss, or almond leaves to the Aquarium.

How to lower pH in the Aquarium with vinegar?

You can lower pH in the Aquarium with vinegar by adding the requisite drops to the fish tank and following the steps that we mentioned in the section titled “How To Lower pH in an aquarium with vinegar.”

How to maintain a stable pH in an aquarium?

You can maintain a stable pH in an aquarium by periodically cleaning the fish tank and removing ammonia, iron, heavy metals, chlorine, algae, etc., from the tank. If the pH level gets significantly lowered, you can increase it by adding baking soda. However, if the pH level increases, you can lower it by using a RO filter or adding natural items like driftwood, peat moss, and almond leaves.

About the author

I'm Gulshan, a passionate pet enthusiast. Dive into my world where I share tips, stories, and snapshots of my animal adventures. Here, pets are more than just animals; they're heartbeats that enrich our lives. Join our journey!thing.