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9 Ways How to Raise pH in Aquarium (And Why You Should Do It)

9 Ways How to Raise pH in Aquarium (And Why You Should Do It)

All aquarium keepers know that keeping stable water parameters is the key to healthy fish. This means you need to know how to raise the pH in an aquarium if the levels become too low.

Making sure your fish have the right type of tank and food is important. However, water quality can be just as important, if not even more! This includes monitoring the pH levels and making sure they are appropriate.

What to do if you notice your pH levels lowering? How to reach the right pH? More importantly, how to do all of this without taking your fish out of the tank or using harsh chemicals? This might sound impossible, but don’t worry – you can do it!

With just a few tips, you can learn how to raise pH levels in an aquarium like a pro! Here’s what you need to do:

How Do You Raise the pH in Water?

goldfish swimming in fish tank

Most aquarists worry about their pH levels being too high or their fish. However, pH levels should almost always be neutral, and not too low or too high. This means that understanding how to raise pH in aquariums should be considered standard knowledge.

The desired levels of alkalinity in a freshwater tank are between 6.8 and 7.8. Anything lower than that is considered too acidic, and anything higher than that is considered too alkaline. Since you’re here, I guess you’re having issues with acidic water.

Luckily, there are safe ways to ensure optimal pH levels without causing unnecessary stress to your fish. No, I am not talking about using homemade aquarium salt, sea salt, or any other expensive item!

Here are 9 tested methods:

1. Aerate the Tank

The first option is to aerate your tank. Many aquarists would claim that this is also the best way to lower the pH levels in the water, but I’ll leave this decision to you.

Aeration is the process during which the oxygen levels inside water are maintained. This includes increasing oxygen saturation, while also lowering carbon dioxide levels. 

When fish breathe – or rather, respirate – they use oxygen and produce carbon dioxide. This process is very similar to the one that occurs in humans or animals breathing outside the water. 

High carbon dioxide levels are harmful for many reasons. First off, carbon dioxide is toxic to fish just like it is toxic to us. However, you might not know that it is also acidic. When you lower carbon dioxide levels, you’ll also lower the pH levels of the water.

You can aerate your tank using several methods, such as:

  • Adding a good filter that will aerate the water.
  • Increasing the number of anaerobic bacteria.
  • Adding underwater plants that breathe in carbon dioxide and breathe out oxygen.

You probably already have a good filter – a sponge filter, I presume, if you have small animals such as baby fish or blue jelly shrimp. If this isn’t enough to keep your carbon dioxide levels low and your pH levels high enough, consider adding plants or good bacteria.

2. Boil the Decorative Driftwood 

Driftwood is one of the common decorative items inside our tanks. It looks pretty, and our fish love it! Chances are even you have one inside your tank (If you don’t, skip this step!).

However, not many people know that it can impact the pH levels inside the tank. In fact, using driftwood is a common method for keeping your pH levels lower.

This is because driftwood releases acidic compounds known as tannins or tannic acids when in contact with water. Just like other acidic compounds, tannins will lead to a decrease in your pH levels. 

Don’t panic – you don’t need to remove your gorgeous driftwood forever. All you need to do is to boil it. 

Boiling the driftwood will prevent it from releasing tannins. While this won’t raise the pH levels per se, this was likely the main cause of low pH levels in the first place. Once you’ve boiled it, you’ll probably notice your pH levels going back to normal quickly enough.

3. Baking Soda 

Baking soda (sodium bicarbonate) is probably one of the first things that fall into your mind. Anyone who is researching how to raise pH in aquariums probably saw this method. But will baking soda raise the pH in your aquarium? 

Baking soda is considered the go-to alkaline solution. It is often used to increase the alkalinity of many things, including even our guts! And it’s easy to see why.

This solution is cheap, and most of us already have it in our kitchens! Also, it’s fairly easy to use. 

All you need to do is to add a teaspoon of baking soda per 5 gallons of water. This amount will slightly increase your pH levels and it won’t harm your fish, shrimp, snails, or plants. You might have to repeat this process every few days until the pH levels are back to neutral. 

Just don’t go overboard with the baking soda, as it might cause your pH levels to become too high. Also, this isn’t a long-term solution. Adding baking soda or any other alkaline chemical for too long might cause more harm than good. 

Always make sure to deal with the cause of the issue. Baking soda is just a method to mask the consequences and raise pH levels for a while. 

4. Aquarium Buffers 

Aquarium buffers are a common chemical solution that works similarly to baking soda – but more effectively. 

These buffers are designed specifically to replenish bicarbonate and carbonate levels and to ensure your pH is properly maintained or increased. You can find them on most pet store shelves and most products aren’t pricey. 

You might also find buffers that will remove carbon dioxide from the tank and replace it with oxygen. This will further help keep optimal alkaline conditions.

However, this means you need to know what is causing your pH levels to drop – but more on that later on. 

Also, most people don’t have aquarium buffers just laying around, which is another reason why you might want to attempt this method. Still, this is probably the easiest way to ensure the pH of your aquarium is high enough – but not too high.

5. Crushed Corals 

Another chemical that helps raise pH is calcium carbonate. Don’t worry – you don’t need expensive solutions to get it. All you need to do is to add some crushed corals to your tank.

No, I don’t mean simply pouring corals inside your tank. This isn’t the right way to do it, as you might raise the pH levels too much too suddenly. 

Instead, take some crushed corals, put them in a bag, and add them to your filter. This will gradually increase the pH values without shocking your fish or making your tank too dirty. 

If you’re having trouble finding crushed corals, a good replacement is aragonite sand. Use it in the same way. 

6. Limestone

Another great method for everyone learning how to raise pH in aquariums is to add limestones to their tank.

Limestones are another great source of calcium carbonate, as well as magnesium carbonate. They are affordable and small in size, so they will easily fit most tanks. They react with acidic water, raising pH levels and neutralizing it. 

This also means that limestones won’t affect alkaline or neutral water levels.

Next to this, adding limestones can have many other benefits. This includes:

  • Lowering the iron levels.
  • Absorbing the excess salt.
  • Reducing carbon dioxide levels.
  • Providing necessary nutrients to the fish.
  • Providing decoration to the tank.

All of these are great reasons to add limestones to your tank.

7. Seashells

Another great source of calcium carbonate is seashells.

From store-bought shells to shells you collect at the beach, all will do wonders for your tank. They’ll reduce acidic levels while providing beautiful decoration for your tank

Of course, you cannot just pick up seashells from the sand and immediately put them inside your tank. You should always boil and rinse them first to make sure there are no harmful bacteria or chemicals on them.

Believe it or not, you can go overboard with seashells. In general, you should add no more than two shells per gallon of water. Don’t expect to see a sudden change. It can take a while for calcium carbonate to react with water.

Also, avoid painted shells. Most paints are harmful to aquatic life, so it’s better not to take any chances.

8. Removing Items that Lower the pH

There are many items found in your tank that are used when you want to lower the pH levels in your tank. You might have them in your aquarium without realizing it. 

We’ve already mentioned driftwood, but this isn’t the only questionable item. The other commonly used ones are peat moss and Indian almond leaves.

Just like with driftwood, removing these items won’t simply raise your pH levels. Rather, this will help get rid of a possible cause behind acidic tank water.

9. Change the Water

Finally, if nothing else works, you might want to consider changing the water inside your tank. 

Regular water changes are a good way to ensure you don’t need to urgently change the entirety of the water, as this might stress your fish out. The best method is to change about 30% of aquarium water twice a month, if not weekly.

By changing the water, you’ll keep the oxygen levels high and other water parameters stable. You’ll also get rid of fish waste and uneaten food. Not just that, but it’s easier to manipulate pH levels when fish aren’t inside the tank. 

Just remember that changing the entirety of the water should be your last resort. Any large changes, such as this one, might cause more harm than good. Fish don’t like being moved around, and if the water parameters are too different than they were before the change, your tank inhabitants might even die. 

Is Low pH Harmful to Fish?

small fish in aquarium

First and foremost, it’s important to understand that not all fish species have the same water requirements. Also, the impact of water hardness might hit various species differently. Freshwater fish have different requirements and tolerability compared to tropical fish.

Even related fish or shrimp species, such as blue bolt shrimp and cardinal sulawesi shrimp, might not have the same sensitivity levels.

Most freshwater species of fish will tolerate somewhat lower pH levels. However, saltwater fish will require higher pH levels. They’ll survive in neutral conditions, but they’ll thrive when alkalinity is between 8.0 and 8.4. 

Levels lower than 6.0 are considered dangerously low no matter the species you have. Such high acidity can burn fish and cause severe harm. Also, this will lead to the growth of harmful bacteria and disrupt the nitrogen cycle, increasing nitrite levels.

Symptoms of Low pH in Fish Tank

While noticing low pH levels is an important skill, it isn’t particularly difficult. You don’t need expensive products and it doesn’t require too much work – although I would still recommend using water testing kits.

Here are some common symptoms of low pH you need to look out for:

  • Algae growth. Green algae thrive in acidic water. Making your tank glass crystal clean isn’t enough. You must deal with pH levels first.
  • Fish become pale. Low pH and oxygen levels can lead to your fish becoming pale and sickly looking. This is likely the first sign of low alkalinity levels you’ll notice, and it results from autophagy by amino acid starvation.
  • Your fish are stressed out. Most fish species are very sensitive to sudden water changes. This includes changes in water acidity.
  • Fish hanging out at the bottom or the top of the tank. This is a sign that your fish are struggling to breathe and that your tank lacks oxygen. Usually, this also means pH levels are too low.
  • Dirty substrate and tank bottom. Green and gray sludge on the bottom of your tank is a clear indication of everything that can lead to low pH levels.

Causes of Low pH Levels

fish in fish tank

You cannot truly understand how to raise pH in an aquarium without learning what causes low pH levels first. 

Sure, the simple answer would be ‘high acid  levels‘, but it’s important to go deeper. Water doesn’t become acidic for no reason. 

Here is what might be causing your water to go to the acidic part of the pH scale:

1. Poor Maintenance 

Lack of maintenance is likely the main cause of low pH levels in your freshwater aquarium. This doesn’t necessarily mean you aren’t taking care of your fish. You simply aren’t doing it the right way.

Fish respiration causes a lack of oxygen. Also, food leftovers, waste, and macro algae can accumulate in the tank that hasn’t been properly maintained. All of this leads to acidic water. 

Poor maintenance can also lead to the old tank syndrome which happens when alkalinity levels suddenly drop. This can easily kill all fish in the tank. 

As mentioned, you should change about 30% of the water every two weeks. You don’t have to remove the fish to clean the tank. Just make sure the water is fresh and full of oxygen.

Just adding a filter isn’t enough. You need to clean your tank properly and you need to do this regularly. Otherwise, your pH levels will go down.

2. Using Tap Water

Using tap water without cycling it first has many dangers. Acidic tank water is one of them. 

While you’ll rarely find water in the U.S. with low pH levels, this tends to happen in various parts of the world. If you plan on using the water from your household for your fish, use test strips  to check pH of your tap water beforehand.

If it’s too acidic, you might need to do some additional steps to ensure the parameters are okay.

While tap water might be okay for our everyday use, it can come in a wide range of pH values. It might also have high nitrate or low oxygen levels! Don’t risk your fish’s health unless you really have to.

3. Bad Air Flow

If you don’t have proper filters inside your tank, this is your cue to go and buy one as soon as possible.

Filters are an essential part of every tank. No matter whether you’re keeping guppies or crystal red shrimp, you need to get a proper filter. 

Any type of filter will do just fine, as long as it can promote the air and water flow inside the aquarium. This is the best way to give your fish fresh water without having to change the water every single day.

4. Excess Tannic Acid 

Any wooden elements inside your tank might produce the tannic acid I’ve mentioned before. If you have too many unboiled driftwood elements, tannins will build up, which will result in acidic water. 

To ensure the pH levels of your water are within a good range, you should boil any wooden elements before you add them to the tank.

Too many tannins can make your water brown and cause pH levels to drop. 

The Bottom Line

Maintaining proper pH levels is extremely important, both in freshwater and saltwater aquariums. Having low alkalinity levels is especially dangerous. Fortunately, it isn’t hard learning how to raise pH in aquariums, even if you’re just a beginner.

With just a few changes, you can ensure your fish will have the best life possible. Regular water maintenance is the key, but there are a few other things that can help.

While perhaps just one of these methods might be enough for you, you can also combine several of them, especially if you have a severe issue. Either way, you should do all you can to make sure your pH is at optimal levels.

Good luck!