4 Simple Ways To Lower Aquarium pH Naturally

Aquariums can be a fun and beautiful addition to any home or business, but keeping your aquarium in good shape and your fish happy and healthy can rely on many factors. The most important of those factors is, in fact, the pH level of your aquarium.

To simplify it, there are two ways your aquarium’s pH balance can be thrown off, and many reasons why they can occur. Your aquarium’s pH can be “normal”, “low”, or “high”, and they each mean something different.

  • What is “Low” pH? – A low pH means that there is an increase of hydrogen ions, making the water more acidic.
  • What is “High” pH? – High pH is due to too many hydroxide ions in the water, making it more alkaline.
  • What is “Normal” pH? – that’s a funny question. As About.com put it, there is truly no “normal” pH amount. There is an optimal pH amount of (approximately) between 5.5 and 7.5 for freshwater fish, but due to the variance of fish species and preferences, you may have some research before picking fish.

Why Does pH Increase or Decrease in My Aquarium?

There are many reasons why your aquarium’s pH can be off-balance, even unexpected things, like the type of gravel or substrate, which can change the pH balance. Decorations are notorious for changing the pH of a tank, and even putting a new water filter in or filling up the water in the tank from a different source can cause problems, so it is important to consider these features before making any changes to a good pH balance.

Substrate and Decoration Problems

Changing the gravel in your aquarium can be one of many causes of a change in tank pH. Because there are so many different types of gravel, make sure that you have the proper type for your fish. For example, crushed coral can be very appealing to the eye, but is best for being used in marine aquariums where fish enjoy a higher pH, but can harm lower pH fish.

Likewise, shell, rock, and other decorations can sometimes leak minerals or dyes into your aquarium, causing a toxic reaction that can be fatal to fish. Make sure you’re getting colorfast inks and dyes in your aquarium decorations.

Water Source and Filter Problems

Even doing a good deed like changing the water in your aquarium can change the pH. If you use a different water source or change a filter, the pH of the tank can vary greatly. The key is to use as little chemicals in the water added to your tank and filters as possible, even tank-specific chemicals meant to help balance out pH as they can drastically change pH.

Four Ways to Raise or Lower pH Naturally

Luckily, there are as many ways to change the pH for the better as there are to accidentally make it worse. The best way to change it is the natural method, as opposed to the chemical method. The chemical altering of pH from the introduction of store bought chemicals can actually alter pH either too much or too drastically – both of which can result in fish illness or death.

The natural way is quite simpler, doesn’t involve harsh chemicals, and won’t make immediate drastic changes that could harm your aquatic life.


Adding a piece of natural driftwood to a tank community can gently help lower pH levels. It is, however, a great way to color your tank’s water, so to avoid that, it is recommended that you either soak your driftwood in a separate container (completely submerged, not floating) for 1-2 weeks prior to introducing it to your tank, or boil it to sterilize it.

Adding Driftwood – Simplest Way To Lower pH Naturally

The wood acts as a filter for the water similarly to how the leaves of a tree would filter air, in that the composition of the tree acts as a natural filter for contaminants, or, in this case, the contaminants in water that raise the pH value of your tank.

Driftwood sold for reptiles may look great but can also contain chemicals harmful to fish, so make sure that you are purchasing the correct thing.

Peat Moss

Peat can also be a great way to help naturally filter the pH levels of your tank, but, again, can discolor your water. Many aquarists recommend pre-treating your peat moss in a separate bucket for a few days before putting it into your tank in order to dissipate the yellowish tinge that natural peat can give water.

Try adding peat to naturally lower pH

Peat moss can be added to the filter in pellets or chunks that you can purchase at any pet or gardening store, and can naturally lower pH by acting as a second filter. Putting them into a filter bag (or use a women’s panty hose as a filter bag) or inside your water filter itself is highly recommended.

An addition of peat to your tank, whether in natural moss form or pellets, will gradually lower pH over time, so if you’re doing weekly water changes, you might not notice as much of a difference as people who change their water less frequently.

Depending on how hard your water is, you will have to experiment to find the right amount of peat for the size of your tank in order to reach your optimal pH level.

Almond Leaves (Catappa)

Catappa is a type of Indian Almond leaf that acts as the “poor man’s water conditioner,” softening and lowering the pH. Almond leaves can also release an amount of tannins in the water, so you may want to soak them to get the color leakage out prior to adding them to your tank. However, the color difference can usually be fairly subtle, especially compared to other methods that release colored tannins into the water.

Almond leaves – an easy and natural way to lower aquarium pH

Also, Catappa will, without fail, help to naturally lower the pH balance of your tank by filtering the water just as they filter contaminants out of the air. There is also some speculation that almond leaves work as a natural health aid in aquarium fish, and some say that it can prevent or cure disease, working as an antioxidant and anti-inflammatory, but the clinical research to support such claims is still in progress and not yet fully confirmed.

Almond leaves can also be a great aesthetic addition to a tank, especially for fish that are used to a native habitat in a river, lake, or other body of water with lots of natural clutter. Fish love the natural hiding spot and ecological impact that leaves can have on their environment.

RO water

RO water refers to Reverse Osmosis, a process of water purification involving (according to Wikipedia.org) the use of a semipermeable membrane that removes many types of molecules and ions, resulting in fresher, softer water.

The filter allows water and smaller ions to go through while keeping the heavier, larger ions like lead, chlorine, and other water pollutants filtered out for the most part. A good RO system can cost a few hundred dollars, but it is a natural deionizing process that can be used in aquariums easily.

AQUATICLIFE Twist-in 4-Stage Reverse Osmosis Water Filtration Deionization System, RO/DI Filter Unit 75 GPD
Recommended RO unit: AquaticLife Twist-in

An RO unit will help provide a constant, stable pH level, and can filter up to 99% of water contaminants. An RO system will need occasional filter replacements, but is a great long-term solution if you have hard tap water and your fish are not happy in it.

So whether you choose an aesthetically pleasing method like driftwood or almond leaves, or an additional filtering process like peat moss or an RO system, never fear. You can gently and naturally control your tank’s pH with a little information and a little time.

Let us know how these methods work on your tank by commenting below and be sure to help your aquarist friends choose the natural way to balance out their tanks’ pH.


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