Aquarium PH Levels: The Best PH Level for your Fish Tank and How to Safely Adjust It

If you are an avid aquarium keeper, you may have never imagined that you would have to become adept at water chemistry too. If you have found yourself checking, monitoring and testing your pH levels in your tank, then you may benefit from a little bit of extra help and advice. This is where Pond Planet steps in!

We have put together a comprehensive and handy guide that will take you through the basics of pH levels in your aquarium, why it’s essential, and how to safely adjust the levels.

What Is pH And Is It Important? 

pH, or the Power of Hydrogen, is the number of hydrogen ions in a liquid, and this determines the acidity of the water. Measured on a scale of 1 to 14, a neutral pH result is recorded as 7, with pH numbers falling below this classified as acidic. Alkaline, or basic, liquids have a pH level of upwards of 7. 

If you’re wondering why pH is important in your aquarium, consider the different habitats your fish and plant species originate. All of these environments will have a specific pH balance important to that habitat. Maintaining the correct pH level is important, especially if your fish are collected from the wild. The pH levels also must be stable as sudden or drastic changes in the environment can be harmful and sometimes even fatal. 

Does pH Change Naturally?

If you leave your pH balance unchecked, it will change naturally and gradually drop in ageing aquariums. This drop can reach levels low enough to distress your aquatic life, and so you must keep monitoring it. 

What is the Best pH Level?

Unfortunately, there is no ‘one-size-fits-all’ solution when it comes to an optimal pH level for aquariums. The best pH level for your tank depends on the aquatic life that you are keeping. As previously mentioned, aquatic life comes from different environments with different pH levels, so you should consider this before choosing fish for your tank. It is best to have fish accustomed to the same or similar pH levels so that you can keep the aquarium level at a suitable and comfortable level for all inhabitants.

As a general rule, we have found that most freshwater tropical fish are most comfortable in pH levels between 6.8 and 7.8. However, some species originate from areas where the pH can be much higher or lower than this. 

It is also important to note that fish bred in captivity will not be acclimatised to the pH levels of their native environment. Because of this, when introducing captive-bred fish to your tank, focus on acclimatising them to your existing water chemistry rather than trying to recreate that of their originating habitat.

How to Adjust Your Aquarium pH

Usually, it is best to not change or adjust your pH levels as there are only certain occurrences where it is necessary. For example, if you are trying to breed your fish, you may need to adjust the pH levels in the tank. Otherwise, if your fish are happy and thriving or you are just keeping fish for fun, there is no real reason for you to adjust the pH levels. 

If you are still keen to learn more about adjusting pH levels in your aquarium tank safely, then keep reading for our basic breakdown of advice for both lowering and raising pH. 

How to Lower pH in Aquariums

To lower the pH levels in your aquarium, there are a few tricks that you can try. 

Firstly, utilise reverse osmosis (RO) or deionised (DI) water to alter the pH levels in your aquarium until you reach the desired level and provide buffering. However, make sure that you always prepare the water and test your pH before adding it to the tank water. You can do this using a water test kit.

Another tip for lowering pH in your aquarium is to add natural driftwood to your tank. Not just a decoration, natural driftwood will release tannins that can help to lower pH, although you should consider that it will take a substantial amount of driftwood to achieve the desired result. For example, in a large aquarium, just one or two small pieces of natural driftwood will not do much, so plan accordingly. 

Finally, consider adding peat moss or peat pellets to your aquarium filter, as similar to natural driftwood, peat moss and pellets contain tannins that lower pH levels. Keep it contained in the filter in a mesh media bag, and make sure you replenish it as needed to maintain your desired pH level. 

How to Raise pH in Aquariums

If you’re looking for a way to safely raise the pH level in your aquarium, you can use the same advice for lowering it that we mentioned above. By utilising reverse osmosis (RO) or deionised (DI) water to alter the pH levels in your aquarium, you can alter the pH level accordingly as well as provide buffering. Don’t forget to prepare the water first and test your pH before adding it to your aquarium. 

Using an alternative aquarium substrates in your tank can also help to raise the pH level. Consider using crushed coral or dolomite gravel instead. These substrates are calcium carbonate-based gravels that slowly dissolve over time and subsequently raise and buffer the pH levels. 

You can also decorate your aquarium with limestone or coral rock, as with a healthy amount introduced into the tank the calcium carbonate rock can help you to adjust the pH level to your desired level. Try filling a mesh media bag with dolomite gravel or crushed coral and placing it in the filter for a similar effect. 

Next Steps 

By now, you should have a good idea of whether you need to adjust your pH levels or if they are safe to leave alone with occasional monitoring. We recommend sticking to regular water changes to keep your fish, plants and invertebrates happy and healthy. In the meantime, look for more help in our popular collection of aquarium water treatments, filters and test kits available online now.