How To Increase pH Level In Fish Tanks | Aquascape Addiction

How To Increase pH Level In Fish Tanks

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We cover the 5 main ways you can increase the pH level in your fish tank along with some important and helpful information on the factors that influence pH levels in your aquarium.

How To Increase pH Level In Fish Tanks

The pH level in your aquarium is one of the most important things that you need to keep an eye on at all times. The pH level of the water refers to how acidic or basic the water is. pH is measured on a scale from 1 to 14, with 1 being extremely acidic and 14 being very basic. For the most part, fish require the pH level to be fairly neutral, or in other words, a pH level of 7. However, some fish need more basic water, up to 7.5, or more acidic water, sometimes as low as 6.

Fish and plants both require specific pH levels to survive and thrive. Having water that is too basic or too acidic can have truly disastrous consequences on the plant life and on the fish in your aquarium.

So, if the water in your tank is too acidic, you need to increase the pH level. How to increase pH level in an aquarium is a question we are often asked, so we are going to do our very best to answer it right now.

How To Increase pH Level In Your Fish Tank

There are actually a few different methods of raising the pH level in an aquarium. Let’s go over some of the best, fastest, safest, and easiest ways of raising the pH level, or in other words, the things you can do to make it less acidic and slightly more basic.

Add Coral

One of the things you can do to raise the pH level is to add some crushed coral into the aquarium. You can add it in a cloth bag so that it does not get out into the water, or you can also add it into the substrate.

Crushed coral usually contains quite a bit of calcium carbonate, a substance which will raise the pH level. The effect of this will be gradual and fairly slow, so don’t add too much at once because very quick pH changes can kill your fish outright.

Add Dolomite Chippings/Shavings

Another substance you can add to the water in order to raise the pH level is to add some dolomite chippings or shavings into the water. It looks like multi-colored gravel, which is why many people use it for its nice look, but it can also raise the pH level in the water.

Dolomite is very rich in both calcium and magnesium, so it does a good job at raising the pH level. It does work a little quicker than the coral, but this can also be bad due to the quick change that may ensue. The best way to use dolomite chippings is to add them into the filter, at least if you do not want to use them as substrate.

Add Limestone Chunks

Limestone looks very nice, so that is always good, plus it contains a whole lot of calcium carbonate, so it will definitely raise the pH level in the tank. Be sure that you do not use too much limestone because it has quite a bit of calcium, so the pH changes it causes can be quite drastic.

You might want to remove the fish from the water before you make any changes to make sure that the limestone does not raise the pH level too much while the fish are in the water.

Limestone is fairly cheap, which is another reason why a lot of people use it to raise the pH level. There are also some other rocks with lots of calcium that can raise the pH level, ones such as travertine, oolite, tuffa, and aragonite.

Add Macro Algae

Don’t worry, this really is not the kind of algae that tends to explode into huge blooms and take over your aquarium. Macro means big, so this kind of algae is not that small stringy stuff.

Macro algae has the ability to absorb carbon dioxide and other chemicals which can cause the pH level of the aquarium water to be low. This is probably the cheapest option you can go with compared to all of the ones we have looked at so far.

Add Baking Soda

Baking soda is extremely basic, so even small amounts will cause pretty big pH level increases. You do want to remove fish from the water before adding the baking soda, just in case you add too much of it.

1 teaspoon of baking soda for every 5 gallons of water is enough to raise the pH level, but not too drastically. Always be sure to measure the pH level before and after adding any amount of baking soda to the aquarium water.

Factors That Influence pH Levels In Aquariums

Getting the right pH level in the aquarium can be fairly difficult, especially when looking to maintain that level over a long period of time. The problem is that there are many different factors which can affect the pH level in your aquarium.

Let’s go over the biggest factors which can change the pH level in your aquarium right now.

  • One of the things that can change the pH level in your aquarium is the water you use when performing water changes. The best way to deal with this is to simply measure the pH level of the water you use before putting it in the aquarium. That way you can make adjustments to the pH level of the water before you even put it in the aquarium. Using soft water that has been treated and is low in dissolved minerals is often very acidic.

  • Carbon dioxide is known to lower the pH level of the water. CO2 is great for plant life, but not so much for fish. If you are adding CO2 to the water, you might want to add a little less. This way it will raise the pH level.

  • Generally speaking, increased aeration and higher amounts of dissolved oxygen in the water will increase the acidity of the water. In other words, it will lower the pH level. Therefore, you can try making the water less aerated in order to raise the pH level and make the water more basic. This can be a little tricky because your fish do need oxygen to survive.

  • Driftwood (we have covered our top 10 list here) and rocks are often very basic, so when you add them to an aquarium, they can lower the pH level quite significantly.

  • High levels of nitrates can cause a drop in the pH levels of the water. Therefore, if you want to increase the pH level in the water, you need to get rid of nitrates. This is best done with a bottle of nitrate eating bacteria or simply by making sure that your biological filter is working properly.

  • Pollutants, chemicals, toxins, and fish waste, especially ammonia, will cause the pH level in the water to drop. The best way to deal with this issue and raise the pH level is to make sure that you engage in regular water changes to remove these chemicals. Making sure that the filter in your aquarium is working properly will help with this too.

  • Water purifiers are known for lowering the pH level in the water. This is sometimes unavoidable as you might need to use a water purifier for one reason or another.

  • Aquariums that are overstocked can also have a low pH level. This is due to a number of reasons, but the point here is that if you remove some plants and/or fish from the water, it should raise the pH level of your aquarium water.


At any rate, your best bet is to always measure the pH level of the water to make sure that you know where you stand. Once you know, you can take the appropriate steps to raise the pH level and correct the problem.