Raising the pH Level in Your Aquarium

One of our recent articles discussed lowering your aquarium’s pH level and how to do it, and now we will tell you how to raise your pH levels for fish that need a more alkaline aquarium or if your water is too acidic.

As a reminder, 7 is considered neutral, lower than 7 is acidic and higher is more alkaline. To find out why and how you need to check your water’s pH, read this fish tank pH level chart photo.

4c9e476ce1404d714edbfca6bfde8e45 1

We will divide this article into two halves: freshwater and saltwater aquariums as there may be some startling differences. If a method can be used on both water types, we will mention it the first time we write about it.

Freshwater Aquariums

As a general rule of thumb, most freshwater fish prefer a slightly acidic pH ranging between 5.5 and 7.5, though there are always exceptions, so you should make sure to ask your pet shop owner or vet to make sure.

  1. Baking soda

If your aquarium’s water is under 7.2pH, then a cheap method is to use baking soda. One teaspoon of baking soda to every five gallons (nineteen liters) of water is the general recommendation.

First, you should remove all your fish from the tank and place them in another container as stirring in the baking soda may send your fish into shock due to a sudden change of pH level. Wait at least thirty minutes after dissolving all the baking soda in the tank before adding your fish back to their habitat. Do this day by day until your tank reaches the pH level you desire.

  1. Adding Coral, Texas Holey Rock or Limestone

This method could also act to prevent high acidity if you line your aquarium with about one inch (two centimetres) of coral, Texas holey rock or limestone. These substrates, especially limestone, are very alkaline, so they will help raise your pH and add calcium to your water.

It is best to use coral or holey rock as limestone is the most alkaline of the three and could raise your pH higher than you want it to be.

As with baking soda, if you want to use this method, then remove your fish from the tank and wait about an hour after adding the substrate before putting the fish back in. The substrate will gently raise pH over a period of time so it will not shock your fish.

  1. Replace 25% of your water every week

If your pH is too high or too low, this solution covers both fresh and saltwater fish. By removing the older, more acidic water and diluting it with something more neutral, you will lower the pH without having to remove your fish from the tank.

Pre-treat your water before adding it to the tank, especially if your tap water has chlorine in it. Then use your siphon tool of choice to remove the old water before adding the fresh water. This also works with saltwater tanks

  1. Use seashells

When you place clean seashells into a tank they will release calcium carbonate into your water supply. Use two seashells for every gallon (3.8 liters) of water in your tank . Do not use painted shells as they will simply release potentially toxic chemicals into the water.

Saltwater Tanks

  1. Open your windows – increase aeration in your tank

Surprising, no? Often, a low pH level in your water is caused by excess carbon dioxide in the air.

Opening the windows will allow fresh air to circulate and oxygenate your tank. Naturally, this will work for all water types, but it won’t be the best for all climates. In milder climates such as spring and autumn, this could be the cheapest, easiest way to raise the pH in your tank.

Other ways you could aerate your tank would be to clean the protein skimmer regularly, purchase an aerator pump.

or use a bubble wand or fountain. The last two have the added benefit of making your fish tank more pleasing to the eye.

  1. Regular tank maintenance

Saltwater tanks are often self-sustaining. The reason they may develop a low pH over time is due to the production of ammonia created by uneaten food or animal waste. Develop a regular method of tank maintenance to keep your pH stable. Ensure you clean your tank every time you do a partial water change. Don’t overfeed your fish as the amount of uneaten food will correlates directly to how much ammonia is in your aquarium water.

  1. Kalkwasser

Kalkwasser, or limewater, is another additive that you can use to increase alkalinity in your water if it is too acidic. It may require monitoring because kalkwasser can increase the calcium in your water too much and cause other problems, so it is best to add kalkwasser to your top-up water or partial water change to dilute your tank water enough to not cause major issues with calcification.

  1. Use a calcium carbonate reactor with kalkwasser

This gives you all the benefits of kalkwasser without having to worry about the calcium levels becoming too high as they will partially cancel each other out. In this case, the limewater soaks up the excess carbon dioxide made by the calcium carbonate reactor. This would be the most expensive option, though one that would require the least maintenance over a longer period of time.


The best, and simplest ways of raising the pH in your tank, be it fresh or saltwater, is simple maintenance and partial water changes. Make it a habit to clean your aquarium and change the water every two to four weeks in order to keep your pH level where you want it to be. Make sure that there is enough fresh air getting into your tank through whichever method you like to help reduce carbon dioxide.

Leave a Reply

Your email address will not be published.

WELCOME TO Aquarium Chest
aquariumchest.com.com is reader supported. We independently recommend methods, ways, products etc. As amazon associates we receive commission for every qualified purchases. More Details>> 
crosschevron-down linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram