Information, Additives, Freshwater fish, Saltwater fish

Lowering PH In Fish Tank With Baking Soda: True Or False?

Photo of author

by Jason Matthews



If you have heard about baking soda and its pH buffering effects and want to know more, you are in the right place; this trick, in particular, helps raise the pH in your fish tank. Baking soda is sodium bicarbonate, as you are already known. To increase your pH, all you need to do is add a small amount of baking soda to your tank water, whether your tank has fish in it or not.

So how does baking soda helps fight against the pH imbalance in your tank?

It works because of the reaction when you utilize baking soda in your fish tank. The baking soda dissolves into the water, creating sodium hydroxide ions. The sodium hydroxide ions will react with any hydrogen ions present in your tank water, neutralizing them. This reaction will raise the pH, making the water more alkaline.

Baking soda is a versatile product found in many stores at an affordable price. In aquariums, you can also use it to clean your tank in addition to raising the pH. This article will explain how to use baking soda in an aquarium and highlight why you should use it.

API pH DOWN Freshwater Aquarium Water pH Reducing Solution 4-Ounce Bottle
2,371 Reviews
API pH DOWN Freshwater Aquarium Water pH Reducing Solution 4-Ounce Bottle
  • Contains one (1) API pH DOWN Freshwater Aquarium Water pH Reducing Solution 4-Ounce Bottle

Last update on 2023-06-05 / Affiliate links / Images from Amazon Product Advertising API

Baking soda is a versatile product found in many stores at an affordable price. In aquariums, you can also use it to clean your tank in addition to raising the pH. This article will explain how to use baking soda in an aquarium and highlight why you should use it.

How can pH levels affect water chemistry?

The pH of water is measured on a scale that ranges from 0 to 14. According to the scale, a pH of 7.0 is neutral. Anything below that number means conditions are more acidic; at levels above 7.0, you have alkaline water.

pH can affect many other elements of water quality and chemistry in your setup.

If the pH drops below 6.0, the bacteria responsible for getting rid of excess ammonia, nitrites, and other toxic elements from the water start to weaken. The most likely result is an ammonia spike, potentially leading to the death of some fish species.

A pH of 7.0 is considered neutral. Most fish and creatures kept in freshwater aquariums need a pH between 6.8 and 7.6, depending on the type of aquarium they inhabit.

There isn’t a specific pH level that works for all species. Some fish live in a slightly more acidic aquatic environment, while others rely on more alkaline waters to survive.

Therefore, to preserve the health of your aquatic pets, you must first get to know them well. If your aquarium has a pH below the recommended level for the species you are breeding, you can use baking soda to adjust your water to the ideal pH.

How to use baking soda to raise your aquarium water pH?

child measuring baking soda for fish tank

Adding a small amount of baking soda is a standard method that raises the pH of your aquarium water. However, you must do this regularly to maintain results, or the pH will quickly drop to its previous level.


  • One teaspoon of Baking Soda
  • 5 Gallons of water

Add 1 teaspoon of baking soda per 5 gallons of water to raise the pH of the aquarium, but do it slowly so as not to stress your fish.

How to proceed

The easiest way to use baking soda to raise the pH is to add it directly to your tank. In this case, you should add little by little and continuously measure the hardness and pH of the water until they reach the ideal level. 

This method must occur slowly and with as much control as possible; otherwise, you can raise the pH too sharply, causing irreversible damage to your tank.

After adding the sodium bicarbonate to the water in the tank, the water will start to bubble, but this phenomenon will disappear after some time. The bicarbonate will dissolve in the water, so you don’t have to worry about later chemical reactions in your tank.

Some people use another method, not pouring the baking soda directly into their tank. If you choose this life, you must remove some of the water from the aquarium in a bucket and then add the bicarbonate of soda with the help of a measuring spoon. After totally dissolved, transfer the water from the bucket to the aquarium.

When the water in the tank comes in contact with the baking soda, it will dissolve and produce sodium hydroxide ions. These ions will neutralize any hydrogen ions present in the water. Hydrogen ions are responsible for acidifying the water. With those ions neutralized, the pH level in your aquarium will rise.

It is vital to measure the pH level periodically, as sooner or later, the acid neutralizing ability will run out, i.e., the baking soda will have been completely consumed, which results in a return to acidic pH. 

We can call this reaction “buffer capacity.” The time for the water to re-acidify tells us the baking soda’s ability to absorb acids contained in the water. Aquarists refer to this as “the ability to maintain a stable pH.” 

You must remember that the natural tendency of water is always to acidify.. This fluctuation harms your tank’s fauna and flora, causing stress and illness.

Other uses for baking soda in an aquarium

The most famous use of sodium bicarbonate in aquariums is directly linked to its ability to raise the pH and to be used as a buffer in acidic aquariums. But this product still has some other lesser-known and practical uses.

Buffering acid water

The pH is one of the most critical physical-chemical parameters of water that exist in the aquarium hobby. The pH regulates several organic functions in fish, plants, and even the nitrifying bacteria that are important in our filtration system.

In marine aquariums, the concern with pH is low as it varies very little, in an average range of 8.1 to 8.5 due to the high alkaline reserve of salt water. But its variation can be constant in fresh water, depending on environmental factors. This variation causes physiological stress in fish, a dangerous and silent problem.

In addition, pH is of great importance for fish survival, as it interferes with the growth and osmoregulation process. Fish can adapt to a limited pH range, with a gradual deterioration of the organism as the pH moves away from ideal.

Therefore, when we acidify aquariums, due to the already explained buffering capacity, we must use acid to reach the level we want and then a base, thus fixing the pH and avoiding variations.

To lock the pH, we can use sodium bicarbonate since it is an alkaline base that will be consumed slowly, besides being cheap and easily accessible.


Sometimes, when deactivating aquariums, we find stained glass almost impossible to clean. To remove these stains, baking soda helps us very well.

It is a highly efficient product also to absorb stale water odors and is a great ally to degrease, shine and remove stains.

Many people do not like to clean the glass of an aquarium without water because they are not always able to remove dirt, in addition to using toxic products such as glass cleaner, which you should never use in aquariums and terrariums.

Before starting the cleaning process, a tip is to cool the glass by spraying water and then wetting the entire internal and external surface. Never use any chemical product precisely, so there is no reaction, even on the outer parts of your tank. Direct contact of those chemical products with the glass, in addition to causing stains on the surface of the glass, can create future toxic environments.

Some recipes and methods are using baking soda that we can safely use in our dirty or stained aquariums.

First method

  • 5 liters of water
  • 2 tablespoons of bicarbonate
  • 1 tablespoon of vinegar
  • 1 tablespoon of alcohol

Mix everything and then apply to the stains with a soft sponge, removing the excess. After cleaning and drying the glass with a lint-free cloth.

Second method

  • 2 tablespoons of bicarbonate
  • 1 cup of alcohol 70
  • 1 cup of water
  • 1 tablespoon of white vinegar

Mix everything and apply with a soft sponge; you can let the stains soak for a while, then dry the glass with a lint-free cloth.

Whatever recipe or product you choose to clean glass, always use the sponge or fabric in the same direction to avoid stains. Clean gradually, part by part, to prevent the product from drying and staining the glass. Continue cleaning and then drying the parts you are cleaning.

It is always necessary to dry with a lint-free cloth. After the glass is dry, finish with a paper towel or newspaper so that the glass is shiny. In case of persistent stains, dip the sponge in white vinegar and apply it to the stain, then dry the glass.

In CO² reactors

Carbon dioxide, better known as CO2, is one of the main factors to help develop plants in your aquarium.

Naturally, every aquarium already produces CO2 due to several factors; however, the concentration is deficient, and few plants can develop healthy at this concentration, so it is recommended to increase the CO2 levels in the aquarium to reach optimal levels.

In a bottle, you can use the Organic CO2 System (DIY) with added yeast and other substances. The reaction of the bacteria will result in carbon dioxide, so just put a hose with a diffuser inside the aquarium to start raising the CO2. In theory, it is simple, but making homemade CO2 can have numerous disadvantages.

The homemade CO2 generation system occurs through a chemical reaction based on neutralizing the acid with a base generating CO2. For the base, we usually use our dear baking soda.

Benefits of Using Baking Soda in an Aquarium

Apart from raising the pH in your tank, there are many other benefits to using this chemical in your fish tank.

It increases oxygen levels in your Aquarium

Baking soda helps to keep oxygen levels stabilized in your fish tank. This is because it helps break down harmful compounds that consume oxygen, such as ammonia and nitrates. It also removes carbon dioxide from your water by breaking it down in the process.

It removes heavy metals

You will notice that when your tank water becomes acidic, there is a lot of iron in the water. Baking soda helps to remove these metals by breaking them down into salt and water. This makes it much easier to filter out after the baking soda has done its job in your tank.

It Minimizes Cloudy Water

When your water is cloudy, you will notice many solids mixed in with the water. This means that you will often get cloudiness throughout your tank, making it more challenging to maintain suitable conditions in your aquarium. Baking soda helps break down the organics in your tank water, leaving it clear and easy to clean up after use.

It is Useful for Treating Fungus in Freshwater Aquariums

Fungus is one of the most disturbing things to deal with in an aquarium, especially if you are dealing with freshwater aquariums. Most of these fungal infections occur when the water has become stagnant, common in tropical fish tanks. Baking soda helps break down these pathogens, making it easier to clean up the mess that they leave behind.

It Minimizes Stress on your Fish and Optimizes their Health and Growth

By lowering the pH in your fish tank, you will notice that your fish and your aquatic life will respond positively to this change. They will feel more comfortable in this type of environment, which means that you will see them thrive and grow faster than before. Low pH levels mean less acidic and more alkaline, making it easier for fish to breathe in their surroundings.

Reducing the risk of infection as Baking soda is anti-microbial

Baking soda is one of the best ways to fight against bacteria, harmful in high concentrations. It acts by breaking down toxic compounds that promote bacteria growth, including nitrates and ammonia.

It also contains antioxidants, which are necessary for aquariums. These antioxidants help minimize the risk of infection in your fish tank because they will combat free radicals present in your water.

Ideal pH ranges for freshwater fish species

Fish species pH level
Goldfish 7.5
Guppy6.8 – 7.6
Cory Catfish7.0 – 8.0
Killifish6.0 – 7.0
Betta Fish6.5 – 8.0
Angelfish6.8 – 7.8
Neon Tetra4.0 – 7.5
Cherry Barb6.0 – 8.0
Oscar Fish6.0 – 8.0
Bristlenose Pleco6.5 – 7.5
Zebra Danio6.5 – 7.2
Platy6.8 – 8.5
Molly7.5 – 8.5
Discus6.0 – 7.0
Pearl Gourami5.5 – 7.5
Rainbowfish7.0 – 8.0
Green Swordtail7.0 – 8.4

Ideal pH ranges for saltwater fish species

Fish species pH level
Clownfish 7.8 – 8.4
Damselfish8.1 – 8.4
Green Chromis8.1 – 8.4
Cardinalfish8.1 – 8.4
Bicolor Blenny8.1 – 8.4
Clown Goby8.1 – 8.4
Yellow Watchman Goby8.0 – 8.4
Firefish Goby8.1 – 8.4
Hawkfish8.1 – 8.4
Lawnmower Blenny8.0 – 8.5
Diamond Goby8.1 – 8.5
Six Line Wrasse8.1 – 8.4
Royal Gramma8.1 – 8.4
Coral Beauty Angelfish8.0 – 8.4
Rusty Angelfish8.1 – 8.4
Dottyback8.1 – 8.4
Chalk Bass8.1 – 8.4

FAQs about Baking Soda and Fish Tanks

Is Baking Soda Safe for Fish?

The answer is yes. Baking soda is completely safe for your fish, plants, and invertebrates in your aquarium.

Does Baking Soda have a Particular Smell?

The soda has a slight alkaline smell, but it is not unpleasant or strong. Baking soda does not have a bad smell by any means.

Should You Add Baking Soda To Your Fish Tank When The Temperature Is Low?

Baking soda does not raise or lower temperature, so there is no need to add it before your tank starts heating up. An excellent way to know if the temperature of your tank is okay is to look at your thermometer. You will need to add baking soda into the tank just before you add fish and each time after that.


Baking soda works wonders in raising the pH levels of your fish tank. It is safe for fish and any other aquatic life in tanks and helps promote healthy conditions for your plants, alkaline, and hard water fish. 

Remember that baking soda only raises the pH of your tank water, but you can also use it for other utilities in your tank. This article will provide you with the basics of using baking soda for its impressive benefits in your fish tank.


Altun, T., Bilgin, R., & Danabaş, D. (2009). Effects of sodium bicarbonate on anaesthesia of common carp (Cyprinus carpio L., 1758) juveniles. Turkish journal of fisheries and aquatic sciences, 9(1).

April, P. R. How to Reduce the Alkalinity of Aquarium Water.

Atkins, W. R. G. (1931). Note on the Condition of the Water in a Marine Aquarium. Journal of the Marine Biological Association of the United Kingdom, 17(2), 479-481.

Atkinson, M. J., Carlson, B., & Crow, G. L. (1995). Coral growth in high-nutrient, low-pH seawater: a case study of corals cultured at the Waikiki Aquarium, Honolulu, Hawaii. Coral reefs, 14(4), 215-223.

Breder, C. M., & Smith, H. W. (1932). On the use of sodium bicarbonate and calcium in the rectification of sea-water in aquaria. Journal of the Marine Biological Association of the United Kingdom, 18(1), 199-200.

Brockmann, D., & Janse, M. (2008). Calcium and carbonate in closed marine aquarium systems. Advances in Coral Husbandry in Public Aquariums. Netherlands: Burgers’ Zoo, 133-42.

Caipang, C. M. A., Deocampo, J. E., Pakingking, R. V., Suharman, I., Fenol, J. T., & Onayan, F. B. (2021, November). Utilization of sodium bicarbonate as anesthetic during routine husbandry activities in ornamental fish. In IOP Conference Series: Earth and Environmental Science (Vol. 934, No. 1, p. 012001). IOP Publishing.

Cleal, M., Gibbon, A., Fontana, B. D., & Parker, M. O. (2020). The importance of pH: How aquarium water is affecting behavioural responses to drug exposure in larval zebrafish. Pharmacology Biochemistry and Behavior, 199, 173066.

Furtado, P. S., Poersch, L. H., & Wasielesky Jr, W. (2011). Effect of calcium hydroxide, carbonate and sodium bicarbonate on water quality and zootechnical performance of shrimp Litopenaeus vannamei reared in bio-flocs technology (BFT) systems. Aquaculture, 321(1-2), 130-135.

Gabriel, N. N., Erasmus, V. N., & Namwoonde, A. (2020). Effects of different fish sizes, temperatures and concentration levels of sodium bicarbonate on anaesthesia in Mozambique tilapia (Oreochromis mossambicus). Aquaculture, 529, 735716.

Grguric, G., Sondey, C. J., & DuVall, B. M. (2000). Carbon and nitrogen fluxes in a closed seawater facility. Science of the total environment, 247(1), 57-69.


Loyless, J. C., & Malone, R. F. (1997). A sodium bicarbonate dosing methodology for pH management in freshwater‐recirculating aquaculture systems. The Progressive Fish‐Culturist, 59(3), 198-205.

Martins, G. B., Tarouco, F., Rosa, C. E., & Robaldo, R. B. (2017). The utilization of sodium bicarbonate, calcium carbonate or hydroxide in biofloc system: water quality, growth performance and oxidative stress of Nile tilapia (Oreochromis niloticus). Aquaculture, 468, 10-17.

Oliveira, S. R. D., Souza, R. T. Y. B. D., Nunes, É. D. S. S., Carvalho, C. S. M. D., Menezes, G. C. D., Marcon, J. L., … & Affonso, E. G. (2008). Tolerance to temperature, pH, ammonia and nitrite in cardinal tetra, Paracheirodon axelrodi, an amazonian ornamental fish. Acta Amazonica, 38, 773-779.

Roberts, H., & Palmeiro, B. S. (2008). Toxicology of aquarium fish. Veterinary clinics of North America: exotic animal practice, 11(2), 359-374.

Siregar, B., Rachman, F., & Efendi, S. (2019, August). Monitoring the Value of Water Quality and Condition Parameters Using the Open Sensor Aquarium. In Journal of Physics: Conference Series (Vol. 1255, No. 1, p. 012036). IOP Publishing.

Zamora, R. J., Parámetros fisicoquímicos de dureza total en calcio y magnesio, pH, conductividad y temperatura del agua potable analizados en conjunto con las Asociaciones Administradoras del Acueducto, (ASADAS), de cada distrito de Grecia, cantón de Alajuela, noviembre.

Zhang, K., Pan, L., Chen, W., & Wang, C. (2017). Effect of using sodium bicarbonate to adjust the pH to different levels on water quality, the growth and the immune response of shrimp Litopenaeus vannamei reared in zero‐water exchange biofloc‐based culture tanks. Aquaculture Research, 48(3), 1194-1208.


Jason Matthews

My name is Jason Matthews, and welcome to my website. When other kids were bragging about how their dog could sit and roll over, I was bragging about my latest Betta Fish and the cool sea castle I just added to his aquarium. 

Jason aquariume

🐠 Get Your Free Ebook: A Beginner's Guide to Aquariums - Sign Up Now!

Learn everything you need to know to keep fish, including setting up your tank, choosing the right fish, and maintaining water quality. As a subscriber, you'll also stay up-to-date on the latest aquarium products, special offers, and discounts.

Your privacy is important to us. You can trust that we will never share or sell your information, and we'll only send you relevant content.

Leave a Comment