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How To Lower Ph In Your Aquarium. Try These Handy Tips – They Work!

Aquariums are great things to have at home or in offices. Watching fish swim in them is fun and soothing. However, the last thing anyone wants is to see their pets floating dead and not swimming. This can happen if the level of PH is off. One of the common questions asked by aquarium owners is how they can lower PH in their fish tanks safely. It’s important that PH levels remain constant depending on the type of fish kept. In most cases, the PH needs to be on the lower side. But why does it change?

There are several reasons as to why your aquarium PH can change. The most common explanation for this is substrate and gravel. It is important that you invest in substrate that is right for your fish. For instance, coral is bad for fish that need low PH as it causes a high PH. Other things that can lead to PH changes include a filter that doesn’t work properly or tap water. Certain shells, rocks and plants can also adversely cause changes in PH.I’ve written a whole guide if you’re looking for the best aquarium filter. Plus ensuring you’re adequately heating your tank makes a big difference too. Here’s my guide on the best aquarium heater.

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Why monitor PH levels?

There are several reasons as to why aquarists should monitor the PH levels of their fish tanks, with the main one being that can aquatic animals only survive within a particular range of PH. And while this range varies from organism to organism, it is not easy to justify that any particular range is optimum for an aquarium in which many species live. Nevertheless, PH changes have an impact on the fundamental processes that take place in aquatic animals. A good example is calcification in corals which falls as PH reduces. That said, what are the acceptable PH levels?

There is no definite answer to this question but the important thing to know is that acceptable PH levels depend on what species you keep in your aquarium. The PH of natural seawater, which is about 8.2, is appropriate if you have a marine or brackish fish tank.

The good news is that there are several solutions you can use to lower the PH.


An inadequate filtration size or a filter that doesn’t work properly can affect the PH of your fish tank. If the filter is function but the PH is still too high, consider adding another or upgrading to one that is larger. When cleaning your mechanical filter to remove debris, take care not to remove the gunk off the bio filter and instead rinse it gently with water once a month to remove clogs. The bacteria on the bio filter play a vital role in maintaining the balance in your aquarium.

Use driftwood

Adding a piece or two of driftwood into your aquarium is a great way of naturally reducing PH in your aquarium. And while you may be skeptical about this, it’s important to note that there are many contaminants that raise PH levels in your fish tank but driftwood is not one of them. The fibrous and course driftwood is best as it will filter out your water, much like filtering through layers of rock, sand and grit in the earth. Keep in mind that wood changes the color of water. An easy solution is to soak driftwood in water for a few days before introducing it in your aquarium. Also take care not to use wood meant for reptile tanks as they contain chemicals that can prove harmful for your fish.

Use peat moss

Image Source: AlamyThe concept of using peat moss to reduce the PH of your aquarium is the same as that of driftwood and the precautions are the same. Peat moss can discolor water and so you should soak it in water a few days before putting it in the fish tank. Otherwise, it will turn the water brown or yellow with time. Because it will float, it’s recommended that you put it inside a panty hose or filter bag to keep it in place. While peat moss does a good job of lowering the PH in your aquarium in time, it’s important to note that too much of it can make the water too soft and this won’t be good for your fish. Conduct a test run to determine how much peat moss you should use to avoid this.

Almond leaves

Image Source: Practical Fishkeeping MagazineStill on the issue of lowering PH naturally, almond leaves are a good bet and contain several components that correct the PH levels. They also release tannins, which can turn your aquarium water yellow. The good news is that compared to peat moss and driftwood, the color change is barely noticeable. Almond leaves are also good at filtering out contaminants that would otherwise cause a spike in the They also help prevent or cure certain fish diseases and have an anti-inflammatory function as well. Another thing that people love about them is that they look great and add a good vibe to any habitat.

Decrease aeration

Reducing the level of oxygen in your aquarium will in turn cause the levels of carbon IV oxide to increase. More carbon dioxide leads to lower PH levels. This makes for a simple and cost-effective way of lowering PH in your fish tank. You should, however, keep in mind that this is a tricky solution as fish need oxygen to survive. Your fish won’t be able to survive if you leave too little oxygen in the tank.

Reverse osmosis filter

Reverse osmosis is a method of filtering water that is often used in water treatment plants. It utilizes a highly specialized partially permeable filter to remove almost 100% of the contaminants present. A reverse osmosis filter has the capability to allow small ions pass through while deterring the larger ions such as chlorine and lead that are harmful to your fish. You should keep in mind that a quality osmosis filter can be costly but other than occasional filter changes; it is worth the price tag. They can filter out up to 99% of the contaminants, particularly ones that cause a spike in PH levels. The main downside is that they are bulky and as such, only suitable for larger aquariums.


While not advisable, there are certain chemicals that can help safely lower the PH of your fish tank. The problem with this method of adjusting PH levels is that chemicals are extremely easy to add and very strong. Even a drop over the maximum limit can have disastrous consequences on your fish. In addition, chemicals are not healthy and depending on how fragile your fish are, they may get sick. You should be very careful when using chemicals to adjust the PH of your aquarium. Only use them as a last resort after you have tried all of the other options.

Add vinegar

This is another option for lowering PH in fish tanks and works through two actions. The first happens instantly and involves release of hydrogen ions by the acetic acid. This process is known as ionization. Over a period of hours, bacteria and other organisms metabolize the acetate by using some of the oxygen and releasing carbon IV oxide. The main concerns when it comes to using vinegar include consumption of too much oxygen and overshooting the PH by adding too much vinegar.

Test your water tank

Because you can’t tell the PH of your aquarium by just looking, you will need a testing kit or measuring device to know for sure. A good PH testing kit is a key factor to knowing if your aquarium PH levels are appropriate. The API Freshwater PH Test Kit is our favorite. It uses a special liquid whose color changes depending on the PH levels of the water. All you have to do is add a little bit of water to the glass tubes that come with the kit then drop in a few drops of the test fluid. Depending on the PH of your aquarium, the water in the test tube will turn a certain color on addition of the test fluid. And yes, the kit comes with color strips that you compare with the color in the test tube. It comes with 250 test kits to serve you for a long time.

The RISEPRO PH Monitor is another good option. While it is more expensive that the API test kit, it is much easier to use as all that’s required to hang the electronic PH tester on the side of the fish tank with the probes in the water. The display screen will let you know what the PH level of the water is. This kit also measures water temperature, making it pretty cool.


Lowering the PH of your aquarium is not hard. It depends on the size of your tank and the work required. What’s hard is getting the quantities right. For this reason, consider doing test runs with the above methods to see how it goes. They all help lower the PH levels, but at different speeds. Remember too much of everything can be dangerous and work slowly not to compromise the health of your fish. Perhaps it’s time for a new fish tank?