How to Lower Ph in an Aquarium (Without Stressing Your Fish)

Published February 16, 2021
Teenage girl testing the water of a home aquarium

Raising and lowering pH levels in an aquarium is an essential skill for hobbyists. There are natural methods and a few hacks to lower pH in a fish tank. The techniques are easy, and this may save your fish. All species need a specific pH to survive.

How to Lower pH in an Aquarium

Maintaining water quality requires constant monitoring and adjusting. Before adding fish, hobbyists need to use a water test kit to measure the tank's pH, which is its acidity or alkalinity. Alkalinity is if the pH is too high. Any small change in pH may stress the fish and even kill them.

Normal pH

The pH scale runs from zero to 14, and pH 7 is neutral. The water test kit helps determine whether the tank's pH levels need to be lower or higher.

Water pH by comparing the color of liquid

Natural Methods to Lower pH

Using natural methods to lower pH is safer than introducing chemicals into the tank environment. Fish keepers may try several techniques. The rule of thumb is to lower the pH a little. Do not drastically reduce the pH all at once, as some fish and plants do not tolerate pH changes well.


Driftwood releases tannic acid into the water and naturally lowers the pH of your aquarium. Only buy driftwood made for fish tanks, with no dyes, chemicals, or preservatives.

Almond Leaves

Almond leaves help to naturally lower the pH levels in your tank also by releasing tannic acids. The leaves look nice in your tank and provide natural hiding spots for your fish. Replace the almond leaves every six months.

Peat Moss

Put the peat moss in a separate, aerated container of hard tap water. Soak the moss for three to four days before adding it to your aquarium. This step prevents the peat moss from turning your water yellow or brown. Place the moss in a filter bag or pantyhose, so it does not float. Do not add it straight into the tank.

Hacks to Lower pH

Don't let little numbers deceive you. Even a small change may change water chemistry drastically.


When vinegar combines with oxygen in the tank water, it converts to carbon dioxide, water, and bicarbonate. This hack reduces the pH in your aquarium. Do not use more than one mL of vinegar per gallon of water.

Baking Soda

To increase pH levels, dissolve baking soda in some water and then pour it into your water tank. Let your fish adapt to the pH level increase before adding any more baking soda. A general rule is one teaspoon per five gallons.

Baking soda on spoon against background of glass of water on wooden table

What Causes High pH in an Aquarium?

When the pH levels are too high or too alkaline, it may be due to certain stones, rocks, and plants. There is a chance the tank decor is why your water's pH levels are too high. Use your water test kit to quickly evaluate the levels. When you dip the strips of litmus paper in the water, it changes color to indicate the pH level.

The pH Levels May Go up or Down

When there are regular water changes, fish show better coloration, live longer and healthier lives. Water changes may help the pH levels from going up and down. With that in mind, if the pH of the water is too high, you can always lower it. Don't panic!

Hobbyists Need to Know How to Adjust pH

Carefully research the pH of any species you purchase for your tank. When the pH levels are too low, it is due to acid buildup. If the pH levels are too high, rocks and plants are causing the water to change. Cleaning and maintaining the water may solve the problem. Natural methods are always safer than adding chemicals and quickly solve the problem.

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How to Lower Ph in an Aquarium (Without Stressing Your Fish)