Aquarium pH

aquarium water ph testWhen you read Tropical Fish Profiles, you will notice a suggested or needed Aquarium pH level for that particular tropical fish. Many people are confused as to what the pH is, or how you manage it.

First, let’s identify what the abbreviation “pH” represents. pH stands for potential hydrogen. In other words, pH measures how acidic or alkaline the aquarium water is in your fish tank.

Aquarium pH is measured on a scale between 0-14.0. Aquarium water pH that measures 0-6.9 is acidic, while a fish tank pH measuring 7.1-14.0 is alkaline. Aquarium water pH of 7.0 is neutral.

Aquarium Water pH Effects on your Tank

The pH level in your freshwater tropical fish tank effects many aspects of your aquarium water. Aquarium pH levels that measure below 6.0 will slow the Aquarium Nitrogen Cycle. The beneficial bacteria needed to convert the poisonous ammonia must have a pH above 6.0 to thrive and multiply. If the fish tank pH does fall below 6.0, your aquarium tank my go through another cycle. The result may be fatal to your tropical fish.

Aquarium pH and your Tropical Fish

So, is there a perfect measurement of pH in aquariums for all tropical fish?

The answer is no. There is no “one” pH level that is perfect for all fish.

You will hear people in the hobby state that you should keep the pH in aquariums at 7.0. Yes, 7.0 is neutral, and many tropical fish species will live comfortably in this pH range. But you do not need to panic if your pH is not exactly 7.0. Tropical fish do have recommended levels of pH that they will thrive in. Every tropical fish hobbyists wants to match the pH of the natural environment from which or pet fish originate.

Most tropical fish (with the exception of a few species) will live in a wide range of pH levels. I’ve had great SUCCESS in the hobby with aquarium water with pH levels between 6.8-7.8. Aquarium pH levels may effect growth, coloration, and breeding among certain types of tropical fish.

Test your Water Source

I highly suggest you test your water source before purchasing your tropical fish. This will ensure that you know what range your Aquarium pH falls into. Knowing the fish tank’s pH level will give you a good idea on what type of tropical fish you can keep. Unless you have odd water conditions in your home, or you want to keep a more exotic fish, you should be just fine with your aquarium pH level.

To get an accurate reading on the aquarium water pH straight out of your tap, first you need to fill up a cup or bucket with tap water. Second, you will need to add an airstone to add oxygen to the water. Leave the airstone running in the water for 24 hours and then test with a high quality Freshwater pH Aquarium Test kit.

Adjusting your Aquarium Water pH

There are many people that make the mistake of trying to adjust their aquarium water pH to meet the exact “suggested” pH levels of the tropical fish they are keeping. This can be a huge mistake.

The most important thing regarding pH in aquariums is to keep the levels consistent. You will do way more damage to your tropical fish and water parameters when you try to raise and lower your pH. Keeping your fish tank pH consistent ensures that your fish have a steady environment.

Drastic changes in water quality including dramatic changes in you pH can put your tropical fish in shock often resulting in death. When the aquarium water pH levels rise, the toxins such as ammonia become more toxic. It is very important to test your aquarium pH levels weekly or every two weeks especially during the first months your tank is set up.

Please note that I DO NOT suggest dosing chemicals to raise or lower your aquarium pH.

Raising your Fish Tank pH

  • Adding a crushed coral substrate can help raise and buffer your aquarium water pH.
  • Certain rocks can help raise and buffer your aquarium pH. Limestone rocks such as “Texas Holey Rock” and clean base rock used in saltwater tanks (dead live rock that is cleaned and 100% disease and bacteria free).
  • **Baking soda can be used to raise and lower your pH.
  • **Chemical additives


Lowering your Fish Tank pH

  • Add clean driftwood to your tropical fish tank. Driftwood releases natural tannins that are harmless. The tannins lower the aquarium water pH but also will leave your water stained. Your water will look like tea. Regular water changes and patience will eventually lead you to clearer water.
  • Add peat moss to your system. Many add peat moss in their aquarium filter. Water running through the media bag filled with peat moss will often help lower your pH.
  • **Chemicals Additives

**I must state again that I do not recommend adding chemicals or other additives to raise or lower you pH unless you are dedicated to adding the chemicals everytime you perform a water change. Any swing in your pH may lead to diseases or even death of your tropical fish.

pH Buffers

If a higher pH is what you desire, and you have a problem with your aquarium’s pH, you may want to help buffer your water. pH buffers come in several different types but most are powders that can be added to your tropical fish tank and will help stabilize your aquarium pH. If you desire a higher pH in your aquarium water, you may also want to try to add a crushed coral substrate. This is a natural buffer and will prevent your pH from declining rapidly.

pH Aquarium Tips

  • The most important thing to remember is keep your aquarium water pH consistent. Constantly trying to change your pH can do way more damage to your tropical fish.
  • Maintain a strict schedule of water changes to ensure high water quality and this will prevent your pH from swinging back and forth so much.
  • If you decide to dose additives, be sure to follow the directions on the manufacturer’s label. Remember you must dose each time you change your aquarium water.
  • When acclimating new fish, acclimate them slowly. Drastic changes in the aquarium water pH will injure or kill your tropical fish.
  • Test your aquarium pH at least every two weeks to ensure everything is as it should be in the aquarium water.
  • Test your water source and determine if the fish you desire to keep will live comfortably. Most often as long as you keep the pH consistent you will be just fine!

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