Having high nitrites in your fish tank is a sign that there may be something wrong with your fish tank ecosystem. You can do a few things to lower nitrites in your aquarium water.
In general, in order to immediately lower your nitrite levels within your fish tank, you’ll want to do a minimum 25% water change. But this alone will not solve the underlying issue of your aquarium. You may want to dose water conditioners as a precaution while your nitrogen cycle stabilizes.
The number one reason why you have high nitrite levels within your aquarium is that you do not have an established tank with an established nitrogen cycle.
Another reason you have nitrite spikes is that you’ve either crashed the cycle of your fish tanks or you’ve disrupted the beneficial bacteria within your tank water. This means they cannot process your ammonia and nitrite levels properly!
Remember, lowering your nitrite is just a temporary fix.
You need to understand what is causing your nitrite spikes in order to address the root causes and create a healthy environment for your fish.
Below, I’ll go over what causes a build-up of nitrites in aquariums, understand the nitrogen cycle, and how to lower your nitrite levels.
What Causes High Nitrites In Aquariums
The reason you have high nitrites in your aquarium is that you don’t have enough beneficial bacteria to convert nitrite into nitrate.
In a properly cycled aquarium. There should be enough nitrifying bacteria to create an environment with 0 ppm ammonia and 0 ppm nitrite levels and a build-up of your nitrate levels.
I recommend testing your aquarium water with test strips or the API freshwater fish master test kit. You can check the prices on Amazon here.
Using test strips or a test kit is the only surefire way to understand where your nitrite levels, ammonia levels, and nitrate levels are within your aquarium.
There are many causes for a spike in nitrites. It can be from:
- Over Feeding: the excess waste can spike ammonia levels, which can then spike your nitrite level
- Over Stocked/Crowed Fish Tanks: having too much fish poop and waste production can cause a spike in elevated ammonia and nitrite levels.
- Decaying Organic Matter: Leaving dead fish, plants, and food in your tank can create a spike in ammonia levels and your nitrite levels
So, if you have an established cycled tank with cycled filters, your nitrite spikes may come from the above reasons. (if this is the case, then just cut back on feeding, do some tank maintenance, and then test your water again to see if this fixes your issues)
But, another common reason your nitrite is spiking comes down to your aquarium not having an established nitrogen cycle or enough nitrifying bacteria to handle the bio load of your tank.
So, let’s talk about what the nitrogen cycle is and why it’s important to establish one within your aquarium water.
Understanding The Nitrogen Cycle
The nitrogen cycle is the process where beneficial bacteria, also called nitrifying bacteria, convert ammonia to nitrite and then nitrite to nitrate.
Ammonia and nitrite are very dangerous to your fish. Nitrite poisoning and ammonia poisoning are common issues with newly set up aquariums.
Nitrate, on the other hand, is the least harmful to your fish.
You can read this post on signs of a cycled aquarium to learn more about the cycling process and the different ways to cycle a fish tank.
This is why you need to have enough nitrifying bacteria built up within your tank and filters to be able to process your ammonia levels and nitrite levels.
Having Enough Beneficial Bacteria In Your Tank
You need to remember the beneficial bacteria within your tank can only handle a certain amount of “work.”
So make sure you are mindful of the addition of fish, feeding, and maintaining your tank. To avoid unnecessary spikes.
That’s because…
When you first cycle a tank. The colonies of nitrifying bacteria will be able to process the amount of ammonia it was being given during the cycling process.
But as soon as you add fish and feed your fish, fish waste builds up, plants die and decay, and then an ammonia spike can happen.
The sudden influx of ammonia can build in your tank, and your bacteria can only process so much of it.
Slowly, your bacteria colonies will grow to be able to handle this load, but then it will cause the next thing to spike, which is your nitrite levels…
The process repeats where your bacteria will grow to be able to handle your nitrites but then will see nitrates increase.
This is why you should always remember…
Your tank cycle is a living, breathing ecosystem. The sudden introduction of too many fish at once can cause a cycle to crash. The same is true of the buildup of waste materials and decaying organic matter.
Also, if you do maintenance and clean your filters with tap water, it can kill off the beneficial filter bacteria, leading to a crash in your cycle, too!
Now that you understand what the nitrogen cycle is, how to prevent crashing your cycle, and the importance of beneficial bacteria, let’s talk about how to lower nitrite levels within your tank.
How To Lower Nitrite Levels In Your Fish Tanks
Another quick reminder that a rise in nitrite levels is a sign of poor water quality.
You can use the steps below to lower your nitrite levels, but be sure to address the root cause of the problem and what’s causing the spike in the first place.
Do a Partial Water Change To Immediately Lower Nitrite Levels
Doing a water change is the fastest and most effective way to lower ammonia, nitrite, and nitrate within your aquarium.
A 20%-50% water change might be needed depending on your dangerous nitrite levels.
Make sure you are always testing your water parameters with a test kit to know when it’s time to do a water change.
Use Water Conditioners To Detoxify Nitrite Levels
Another way to lower nitrite concentration is to use a water conditioner like Seachem Prime.
Seachem Prime detoxifies ammonia, nitrite, and nitrate within your fish tank. You can check prices on Amazon here.
The idea is not to lower the nitrite levels but to make them harmless to your fish while giving your beneficial bacteria time to grow and process the levels of nitrite within your tank.
Add In Some Beneficial Bacteria To Build Enough Nitrifying Bacteria
You also have the option to introduce more beneficial bacteria to handle and convert the high levels of nitrite and ammonia within your tank to nitrate.
Seachem Stability is a good product for this. You can check the prices on Amazon here.
A recommended method is to use Seachem prime and stability together. They work great hand in hand.
One product detoxifies the harmful chemicals, while the other introduces nitrifying bacteria to handle high nitrite and ammonia levels.
This is a great method for emergencies where you need to do a fish-in cycle, or your established tank cycle crashes for whatever reason.
You’ll be able to dose these two products daily until your cycle stabilizes on its own
Reduce The Amount Of Fish Food You Are Feeding
Cleaning any uneaten food and making sure you are only feeding what your fish can eat within 2-3 minutes is a good way to lower a nitrite spike caused by overfeeding.
The more food your fish eat, the more waste and ammonia they produce.
Clean Up Any Dead Plants, Uneaten Food, And Decaying Organic Waste
Another common reason you may have a spike in nitrite toxicity is letting organic material and waste build up within your freshwater aquarium.
Make sure you are siphoning and cleaning your substrate during water changes and routine maintenance to avoid this issue.
Ensure Your Your Fish Population Is Not Overstocked
Having too many fish is one of the reasons your cycle can crash.
This is especially true if you are adding a lot of fish species all at once without giving time for the cycle of your freshwater tanks to adjust.
Be sure if you are adding fish, you do it in small batches, then give your tank time to stabilize for a week or so, and then add a little more.
Repeat this process until you have stocked your tank with the recommended amount of livestock.
Signs Of High Nitrite Levels
Below are the 3 most common signs you may have high levels of ammonia or nitrites.
- Healthy fish may show signs of rapid gill movement
- Healthy fish start to be lethargic and stay in one spot in the aquarium. Usually, it is either down below, near the substrate, or near the surface of your aquarium water.
- Your fish stop eating food.
Both ammonia and nitrite poisoning can be deadly to your fish. If you see any of these signs, you’ll want to test your water quality immediately.
Frequently Asked Questions
What Causes High Nitrite Levels In Fish Tanks
In general, high nitrite levels can be caused by over-feeding, overstocking, or a build-up of organic matter within your aquarium. It’s also a sign that your tank may not be cycled properly, or your cycle may have crashed.
What Breaks Down Nitrites In An Aquarium
Establishing nitrifying bacteria within your aquarium substrate and filter media will break down nitrites in an aquarium. You can build up this beneficial nitrite-converting bacteria with the use of bottled bacteria like Seachem stability.
Conclusion To The Different Ways To Lower Nitrites In A Fish Tank
This concludes my post on different ways you can lower nitrites in your fish tank.
Now, you should know everything you need to know about what causes spikes, other reasons your tank cycle may be crashing, and different ways to prevent it from happening.
Remember, the main cause of spikes of nitrites is because of insufficient bacteria to process them into nitrates.
This can happen because of an improperly cycled tank, a sudden spike in ammonia causing your cycle to crash, or a disruption in the established beneficial bacteria that can cause your cycle to crash as well.
Ensure you follow the steps listed above to reduce your levels of nitrites, introduce bacteria to help process it, and clean and maintain your tank from any debris that may be causing the spike.
I hope I was able to answer your question and that you found this post to be helpful!
I wish you the best on your fishkeeping journey, and I hope to catch you in another one of my posts!