How To Lower pH In Aquarium - All You Need To Know | Aquascape Addiction

How To Lower pH In Aquarium - All You Need To Know

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A detailed guide on how to lower Ph in your aquarium, everything you need to know with some great, simple but effective solutions

How To Lower pH In Aquarium - All You Need To Know

Aquariums are great things to have around the home, trust me, I have had fish my whole life and it’s really fun. I love to look at my fish swim around for hours on end. Something I don’t like to see however is when my fish are floating dead instead of swimming, which can happen if the pH level is off. “How to lower pH in aquarium?” is a question that many people have.

Depending on the type of fish you have, the pH levels in the aquarium need to be quite specific, or else you risk killing the poor fish. More often than not the pH levels need to be a little on the low side. So, you may be wondering, how exactly do you lower pH in your aquarium.

Why Do pH Levels In My Aquarium Change?

One of the biggest reasons for having a pH level that is too high in your aquarium is because of gravel and substrate. You need to buy substrate that is the ideal type for your fish. Some substrates like coral can raise pH levels, thus it is bad for fish that need lower levels.

A pH Meter is a handy tool for ensuring you are measuring the pH correctly, we recommend this tool for measuring pH correctly.

AquaFX RO/DI Filter Easy way to keep water at constant pH Level 9.8/10
PH Monitor To Monitor pH Level 9.2/10
API PH Down Chemical pH Solution 8.9/10
Cholla Driftwood Natural pH Solution 9.4/10

Other things that can cause pH level changes include using a different water source such as tap water, or even having a filter that isn’t working properly.

Even certain plants, rocks, and shells that you add into the fish tank can adversely affect pH levels. Thankfully there are a few different ways that you can use to naturally change the pH level in the water.

How To Lower pH In Fish Tanks

Here are 6 effective ways on how to safely lower ph in aquariums;

1. Use Driftwood

One great way to naturally lower the pH levels in the water of your aquarium is to add a piece or two of driftwood. You may think that wood is not going to do much, but that is not the case.

There are many contaminants that can get into your water which raise pH levels and in fact contaminants are one of the biggest causes of high pH levels.

Simply add some driftwood into your fish tank and the wood will filter out the contaminants that are causing the pH spikes. The coarse and fibrous the driftwood is, the better it will be at filtering out your water. This is much like water filtering through the many layers of rock, sand, and grit in the earth, thus coming out clean on the other end.

Something to keep in mind is that some woods will alter the color of your water. An easy way to solve this problem is to soak the wood in some water for a few days before introducing it into your aquarium.

Another side note is that you probably shouldn’t get wood meant for reptile tanks because they often contain chemicals which can leach into the water and hurt your fish.

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2. Almond Leaves

The second way that you can naturally lower the pH levels in your aquarium is to add some almond leaves into the mix. There are several components present in these leaves that work to naturally lower the pH levels in water.

That being said, they do also release tannins and will turn your water slightly yellow. However the change in water color is barely noticeable when compared to other things like driftwood or peat moss.

Not only do almond leaves have components in them that work to lower pH levels, but just like driftwood they also serve as a filter. They are great at filtering out contaminants in the water which would otherwise cause the pH levels to spike.

Something that people also like about almond leaves is that they are said to be great for the health of your fish. They are known to prevent or even cure diseases and they have a slight anti-inflammatory function as well. Another thing that people like about them is that they look nice and add a great vibe to any natural habitat.

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3. Peat Moss

Another great way that you can lower the pH level in your aquarium involves using peat moss. Now this is pretty much the same concept as the driftwood, plus it has the same precautions too.

Peat moss can discolor the water and thus you should soak it in a bucket for a few days before adding it to your aquarium. If you don’t do this, the peat moss will start to turn your water yellow or even brown over time.

Peat moss is a great filter for any contaminants that may be adversely affecting the pH levels in your fish tank. In fact it might even be better than driftwood. This is because peat moss comes in small chunks that are very porous and have the ability to suck up and filter out a large amount of contaminants.

Since peat moss will float, it is not recommended that you add it straight into the fish tank like you would with a piece of driftwood. Instead you should put the peat moss inside of a filter bag or even some panty hose in order to keep it in place. You can even put the peat moss directly into the water filter in your aquarium.

Peat moss will lower the pH levels in the aquarium over time, however you should know that too much of it can make the water too soft. Too much peat moss will lower the pH levels drastically and that is not good for your fish either. You will need to do some trial and error to test how much peat moss your specific aquarium needs.

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4. A Reverse Osmosis Filter

Reverse Osmosis is a way to filter water and is often used in water treatment plants. It uses a highly specialized partially permeable filter that removes almost all contaminants from the water. A reverse osmosis filter has the ability to let smaller ions pass through it while filtering out the larger ions such as lead and chlorine (we have covered some good dechlorinator options here).

It should be noted that a good reverse osmosis filter can cost be quite costly, but aside for occasional filter changes these things are well worth the cost. They are perhaps they easiest way of keeping your water a constant pH level without having to do much work.

These things can filter out up to 99 percent of all contaminants in the water, specifically those that cause pH levels to rise. On another side note, reverse osmosis filters can be quite bulky and thus they are really only ideal for larger aquariums.

5. Decrease Aeration

If you decrease the levels of oxygen in the water it will have the effect of causing the levels of carbon dioxide to rise. The more carbon dioxide is in the water, the lower the pH level in the water will be.

Therefore if you need to lower pH levels, simply decrease the aeration in your aquarium. You should note that this is a tricky process because fish do need oxygen to survive. Too little oxygen in the water and your fish won’t be able to breathe.

6. Chemicals

Ok so there are obviously chemicals you can buy to either increase or decrease pH levels in your aquarium. The problem with chemicals is that they are very strong and it is extremely easy to add too much. Even just a drop too many will have disastrous consequences for your fish.

Plus chemicals just aren’t healthy and depending on the fragility of the fish you have, they may get sick from them. If you are going to use artificial pH changing chemicals you need to be very careful. It is recommended that you try any of the above methods before attempting this one.

Testing Your Water

Of course you can’t see the pH levels in the water by eye. You need some kind of measuring device or testing kit to actually know what the pH levels in your aquarium are.

A good pH testing kit is a key factor in knowing what the levels in the water are, so if necessary you can do something about it. Here are two great pH testing kits that you can easily use at home.

API Freshwater PH Test Kit

This is perhaps the simplest method of testing your pH levels in an aquarium. It’s a simple test kit that involves a special liquid which changes the color of the water according to the pH levels.

All you need to do is take a little bit of water, add it to the glass tubes that come included, and drop in a few drops of the test liquid. Depending on what the pH level in the water is like, the test tube water will turn a certain color when the testing liquid is added to the aquarium water.

This test kit comes with color strips included, so all you have to do is to compare the color in the test tube with the colors on the strips to figure out where the pH level is at.

This kit comes with 250 tests and will last you quite a long time, not to mention that it doesn’t need calibrating like the electronic versions. Even though this test kit doesn’t involve any fancy electronics, it is still very reliable and accurate. This is a very cheap way to test the pH levels in your fish tank.

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This version of a pH tester is much easier to use than the test kit above, however it is also quite a bit more expensive. All you need to do is to hang the electronic pH tester on the side of your aquarium with the probes in the water.

It doesn’t need to ever be removed or replace. Simply look at the display screen to see where the pH level is sitting at. A great part about this method of testing pH levels is that it constantly measures the changes in the water and shows them to you instantly.

Another cool aspect is that this particular pH monitor also measures the temperature of the water in your aquarium, something which also needs to be done to ensure the health of your fish. (Aquarium thermometers come in handy here). This method is also quite convenient because this monitor can be powered by either an AC power adaptor or with batteries.

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Commonly Asked Questions

What is aquarium pH?

pH is a measure of acidity and alkalinity, how acidic something is. pH is measured on a scale from 1 to 14, with 1 being the most acidic, like battery acid, and a 14 would be super basic, something like Sodium hydroxide, with 7 being neutral, so neither acidic nor basic.

When it comes to your aquarium, pH therefore refers to how basic or acidic the water is, and yes, this is very important for fish and plants, as various fish and plants require different pH levels.

Will vinegar lower pH in aquarium?

Yes, vinegar is very acidic and will therefore lower the pH in an aquarium, or in other words, make the water more acidic.

When it comes to lowering pH in aquariums, for saltwater tanks, you can use some distilled vinegar. Even a very small amount of distilled vinegar can lower the pH in aquarium water by a substantial amount.

However, if you do not know what you are doing, you really should not be using vinegar to do this. It’s also not recommended to trying reducing pH in aquariums with vinegar in freshwater. It’s best only for saltwater.

Will baking soda lower pH in aquarium?

No, baking soda has a pH level that is well above neutral, or in other words, it’s very basic, with a pH level around 9.

Therefore, baking soda would technically increase the pH level of the aquarium water. If you want to slightly increase the pH of your aquarium, use 1 teaspoon of baking soda per 5 gallons of water.

As an example, if you have a 50 gallon fish tank and want to raise the pH by a full point, so say from 6 to 7, you would need 10 teaspoons of baking soda.

Keep in mind though, baking soda is white and powdery, so it will cloud up the aquarium a little bit.

Can high pH kill fish?

Yes, absolutely, high pH can and does kill fish. pH that is either too low or too high can definitely kill fish.

Now, what the pH level is that will kill fish depends on specific fish. A pH higher than 8.0 is often too high for most fish, and lower than 5.0 is usually too low.

However, you do want to research the specific fish you have for detailed information about this.

At what pH do fish die?

Once again, this all depends on the fish in question. As mentioned above . A pH higher than 8.0 is often too high for most fish, and lower than 5.0 is usually too low.

If you reach a pH level any higher than 8.5 of lower than 4.5, you can be sure that there will be negative health effects, and yes, often death.

What fish can live in high pH?

Some fish that can handle a high pH water level in the aquarium include ones such as koi, which can handle a pH level as high as 8.2 or African cichlids which can handle pH levels up to 8.5. However, there are not many fish which can handle such basic water.

What fish can live in low pH?

Something important to note is that generally speaking, smaller fish have an easier time dealing with low pH levels.

Some of the fish that do well in low pH levels are ones such as tetras, dwarf cichlids and New World cichlids, and plecos, as well as discus and altum angelfish. Some goldfish can do ok in low pG levels too.


How to lower pH in aquarium quickly is really not that hard. Lowering it is the easy part, but the hard part is getting the quantities right (a good monitor like this one does help). You need to do some trial and error with any of the above methods to see how it goes.

They will all serve to lower the pH levels, but some will act quicker than others and some will have a stronger effect. Always remember that too much of anything can be bad, even if it is almond leaves or driftwood. Just be careful and work slowly because the health of your fish is the most important thing here.