Is the pH level in your freshwater aquarium too high? How to lower pH in freshwater aquarium. Worried about it? If so, you’ve come to the right place! I’m an expert on lowering pH in freshwater aquariums. Having kept fish in aquariums for many years, I use my real-world experience to solve pH problems.
One of the challenges beginners face when caring for fish is how to maintain the correct pH level in their aquarium and how to lower it if it’s too high. How to
Ideal pH Values for Freshwater Aquariums
The pH scale ranges from 0 to 14. If the pH of the water is below 7.0, it is considered acidic, and if it is above 7.0, it is considered alkaline. A pH of 7.0 is considered neutral. The pH of water typically ranges from 5.5 to 7.5, which is often referred to as the range of “pure water.”
Causes of Increased pH Levels in Aquariums
Hard Water: If your aquarium water is high in minerals like calcium and magnesium, it can increase the pH level, especially if you live in an area where the water is naturally hard.
Calcium Carbonate Substrate: If you use calcium carbonate or other similar substrates in your aquarium (such as coral sand or dolomite), it can increase the pH of the water.
Decoration: Some decorative elements in the aquarium, such as coral or rocks rich in calcium and carbonate, gradually absorb acid from the water and increase the pH level.
Ammonia: Increasing the level of ammonia in the aquarium can raise the pH level because ammonia makes the water more alkaline.
Unchanged Water: If the water in the aquarium is not changed for a long time, various minerals, excess food, and waste accumulate and decompose, forming ammonia, which increases the pH.
Decreased Carbon Dioxide: Aquarium plants take in CO₂ during photosynthesis and release oxygen. CO₂ dissolves in the water to form carbonic acid, which lowers the pH. When more air flows through the aquarium water (aeration), carbon dioxide is released with the water, which can increase the pH of the water.
Tap Water: Tap water in many areas contains large amounts of minerals, such as calcium and magnesium. If used without treatment, these harden the water and raise the pH level. Therefore, chlorine or chloramine is added to disinfect it.
What are the symptoms of increased pH in an aquarium?
Abnormal fish behavior: Due to increased pH, fish behave abnormally, such as being excessively restless or lethargic, spending more time at the bottom of the tank, or hiding somewhere.
Body color changes: If the pH level drops or rises too much, the body color of the fish fades, and in some species, the color darkens if the pH problem is severe.
Symptoms of breathing problems: If the pH is too low or too high, the fish suffer from breathing problems. This is mainly due to a lack of dissolved oxygen in the water. The fish rise to the surface of the water and breathe rapidly.
Reluctance to eat: If the pH problem is severe, the fish’s interest in eating decreases, which gradually stops completely.
Imbalance: Due to pH imbalance, the fish swim around the tank in an unbalanced manner.
Fin damage: If the pH problem persists for a long time, the fish’s fins can be cut or torn.
Fish death: Fish die if pH problems persist for a long time, especially when the pH level becomes too high (alkaline) or too low (acidic).
How to lower pH in freshwater aquarium
I always use natural methods first when lowering the pH level in my freshwater aquarium because they are easily available, less expensive, and have no side effects. When the pH cannot be lowered using natural methods, I then use chemical methods. Using purchased chemicals can drastically change the pH level, which can stress my fish and make them sick.
Natural Methods:
Change the tank water
When the pH in my fish tank increases, I first change 15-20% of the tank water because fish feces, food scraps, and other waste products accumulate in the aquarium. These waste products decompose and produce ammonia and nitrite, which increase the pH. Changing the water removes these harmful substances, helping to lower the pH.
Use peat moss
I use peat moss to lower the pH inside my freshwater aquarium, which is a great natural way to filter out contaminants in my water. Peat moss releases two substances called tannic and gallic acids that attack the bicarbonate in the water, lowering the pH and reducing the hardness of the water.
How to use peat moss
Before using peat moss directly in the aquarium, wash it thoroughly to remove any dirt or excess material. In my opinion, the easiest way to use peat moss is to place some in the media chamber of an aquarium filter. It will slowly dissolve in the water and lower the pH. I use peat moss in the media chamber of the filter.
If you do not want to put peat moss in the filter, you can add it directly to the aquarium water. You can use a small filter bag and hang some peat moss in the water. This will mix directly with the tank water and help to gradually lower the pH.
The effect of peat moss can drastically lower the pH, so use small amounts at first and observe the effects.
Note: The color of the water may become slightly yellowish or brown when using peat moss, which is natural and not harmful. However, it will clear up soon.
Catappa (Indian Nut) Leaves
Indian Nut (Terminalia catappa) leaves are a popular way to lower pH in aquariums, and I have no problem collecting fresh or dried catappa leaves from pet stores worldwide. They contain weak organic acids. Contrary to popular belief, this acid can actually help lower the pH of high KH water.
Use Catappa (Indian Nut)
Before use, wash the leaves lightly to remove any dust or dirt. Place one catappa (Indian Nut) leaf for every 10-20 gallons of water directly in the aquarium. The leaves will slowly soak into the water and begin to release tannins, which will help lower the pH of the water.
If you do not want to add Indian Nut leaves directly to your aquarium, you can add a handful of leaves to some aquarium water in a separate container and pour the water out when you do your water changes.
Start with a small amount of catappa (Indian Nut) leaves to avoid changing the pH too quickly, and increase gradually. Changing too quickly can be harmful to the fish.
Note: The water may turn slightly yellow or brown due to the tannins released from the leaves, which is not harmful. However, it will clear up soon. If you do not like this color, you can reduce it by using an activated carbon filter.
Driftwood
Another popular method to lower the pH of aquarium water is to add driftwood. When driftwood is placed in water, tannins are slowly released. These tannins gradually lower the pH of the aquarium water and make it acidic. The natural release of tannins leads to a stable decrease in the pH of the water, which is safe and beneficial for the fish.
Moreover, when tannins are released into the water, they help prevent bacteria and fungi, protecting the health of the fish. This helps to increase the natural immunity of the fish and protects them from diseases.
How to use Driftwood
Before using new driftwood, soak it in boiling water for a few hours to remove dirt and excess tannins and prevent it from floating in the water. Boiling water helps to kill germs and remove dirt from the driftwood. Failure to do this can quickly change the color of the water.
Note: Driftwood, like making tea, releases tannins, which may give your tank water a slightly tea-colored or brown hue, but this is not harmful.
If you want to reduce the color of the water, you can use an activated carbon filter, which will absorb the tannins and keep the water clear.
Using an RO/DI System
An RO/DI system (Reverse Osmosis/Deionization System) is an effective and popular method for lowering pH in an aquarium. This system helps reduce the hardness and acidity of the water, creating a healthy environment for fish and plants. An RO/DI system is basically a filter that removes almost all impurities from the water that goes into it.
You should buy a quality RO/DI system, which filters out minerals and other dissolved solids (TDS) from the water. This process removes 95-99% of the minerals from the water. (Instructions for use are written on the product.)
Note: Do not lower the KH too much. Using an RO/DI system will lower the KH, which can make the pH very unstable. Keep the pH stable by adding a KH buffer.
Chemical Methods:
If the problem is not resolved using natural methods, chemical methods should be used. Chemical application should be the last resort to solve any aquarium problem. Many pet stores sell pH-lowering solutions that can be added directly to the water to lower the pH. However, you need to be careful about the dosage and the amount you use. A common mistake can be fatal for your fish.
Warning: Always consult a veterinarian before using chemicals to lower the pH in your aquarium.
Preventing pH Increase
Rather than knowing how to lower the pH in a freshwater aquarium, you should focus on preventing the pH from increasing. If the pH increases, it can cause a lot of harm to the fish, and you will face problems in reducing the pH. Therefore, it is better to prevent the pH from increasing.
- Regular water changes and cleaning: Change 20-25% of the water every week.
- Avoid using pH-increasing materials such as hard water or mineral-rich rocks. Calcium or carbonate-rich rocks, such as limestone, marble, or coral sand, can increase pH.
- Provide good filtration to remove unnecessary waste accumulated in the water.
- Use RO or distilled water to reduce the density of the water.
- Feed the fish in moderation and remove leftover food.
- Regular pH testing and natural pH control are important.
- In most cases, it is better not to use chemical solutions to change pH, as these are not long-term solutions and can ruin the overall quality of the water.
