Get rid of Ammonia and Nitrite in your aquarium… For good.
An aquarium with ammonia and nitrite is the worst headache for any aquarist. Both ammonia and nitrite are extremely toxic to any aquatic life, even including your plants, and will quickly build up and kill everything alive in your tank. We’ll explore every solution to get rid of these two toxins, and explain how to be rid of them for good.
Preface: Testing
A test kit is crucial in the aquarium hobby. It is arguably more important than water conditioner. It is nearly impossible to know what is going on in your aquarium by looking at it- your fish will only exhibit signs of problems once the water has been problematic for far too long. Especially when you are setting up a new tank, you need a test kit of some variety.
Your test kit also needs to be able to test for Ammonia, as that is the most common cause of fish deaths, and first thing released as things decay. Many test strips only test for nitrites and nitrates, and those are useless if your tank is new because there is no bacteria to convert the ammonia into nitrite.
We strongly recommend the API Master Test Kit, which is generally very accurate and easy to use. It’s a little expensive, but $35 is much cheaper than losing $100 worth of fish.
Aquarium Co-Op’s test strips are apparently some of the most accurate test strips available, but they do not test for ammonia, so you’ll need some other test strips specifically for ammonia testing.
Recap: The Nitrogen Cycle
The nitrogen cycle is a term for the way that aquariums are kept alive. Beneficial bacteria grows on your substrate and in your filter, and converts toxic ammonia and nitrite into nitrate, which is safe for livestock (unless it is extremely high) and provides nutrients for plants.
The basis of the cycle is this:
1. Organic stuff like fish poop and dead plant leaves decay in the water.
2. Ammonia is released as stuff decays.
3. The bacteria converts the ammonia into nitrite, which is still toxic to livestock.
4. The same bacteria converts the nitrite into nitrate, which isn’t toxic.
5. Plants absorb the nitrate as fertilizer, or nitrate is removed via water changes.
Any tank with an incomplete cycle doesn’t yet have enough bacteria alive in it’s filter and substrate to properly keep up with the amount of things decaying in your tank. The solution is almost always to simply wait, and the bacteria will eventually balance out so that the tank is stable.
If there is ANY ammonia or nitrite in your aquarium, do a 75% water change immediately.
Causes of ammonia and nitrate in new aquariums
(And why cycling might not be working)
If your tank is less than 2 months old, it likely isn’t fully stable and established yet. Cycling a tank can take anywhere from a week to a few months, and in the meantime you may have spikes of ammonia or nitrate.
Check out our in-depth guide on quickly cycling a tank here!
While your tank is cycling, you should conduct daily or or semi-daily water changes, even if you don’t have any livestock in the tank. Too much ammonia can dramatically slow down a cycle or cause it to crash. If you have ammonia in your tank while you do have livestock, you should conduct a major 75% water change immediately and continue doing so daily until your tank no longer has ammonia.
It is a common misconception that water changes stress fish- While this is true to an extent, it’s far less dangerous to your fish than them living in toxic water.
If your tank continues to test for ammonia even after a few weeks of cycling, consider these factors:
Filter Media - You should never change your filter media or use disposable cartridges. Your filter should have lots of places for bacteria to live, such a sponge, bio-media, etc. You shouldn’t clean your filter while the tank is cycling unless it is so dirty that it’s impeding flow.
pH - Higher pH levels (7.5ish or above) can dramatically slow down cycling speeds. Try adding driftwood or adding small amounts of citric acid to the water.
Temperature - Set up your heater when you start cycling your tank. Warmer temperatures cause bacteria to multiply faster and thus cycle faster.
Organic Matter - The bacteria needs something to eat to multiply, so you should add something to decompose in your tank, like a big pinch of fish food. However, if you have too much gunk in your tank, your ammonia will be way too high.
Not enough oxygen - The bacteria in your filter needs oxygen to thrive. If your filter has very low flow, they might not be getting enough oxygen. Try adding a bubbler or increasing your filter’s flow rate.
Chlorine - Make very sure the water in your tank does not have any chlorine, and that your tank is clean of soaps or cleaning chemicals. Any chlorine or soap will completely kill off all the bacteria in your tank and filter.
Ammonia IN your tap water - A few places may actually have small amounts of ammonia in their water supply, which obviously will add it into your tank even after doing a water change. Consider testing your tap water for ammonia too, and use a water filter if it has some. For your health, too.
Ammonia in mature aquariums
I don’t usually test my water on a routine basis for mature aquariums, as I’m confident that my filters are able to keep up with the bioload of the fish and that my plants will take care of any problems. However, the moment I begin noticing my fish acting weird, looking weird, or gasping at the surface I immediately test my water for ammonia and nitrite. So let me reiterate again:
If you have fish in your tank and your test shows you have any ammonia or nitrite at all, do a major water change immediately, and do it daily until it’s fixed.
Ammonia spikes in mature aquariums are generally caused by an issue other than cycling, as the term “mature” assumes your tank has been running for long enough to be cycled and stable. They can be caused by a variety of issues, so let’s explore them:
Changing your filter media - Remember that disposable filter cartridges should never be used because you’re just throwing away all the bacteria grown on them, and the bacteria is what keeps your water safe. Similarly, you should avoid changing your filter media all at one time- if you need to replace a filter or a sponge you should use the old media for a few weeks until the new media has time to cycle.
Overstocking your tank - This is honestly much less of an issue than most people think it is. Overstocking can absolutely cause spikes in ammonia due to the increased waste, but keeping fast-growing plants in your tank will help balance this out and keep the water stable. Mature tanks should be able to adapt to new stock pretty quickly, but if you just recently added a bunch of fish you might need to do water changes until your tank can catch up.
Lots of stuff dying - Did a huge pleco die and you didn’t notice? Is there a rotting snail in the back of the tank? Did a big plant get uprooted and rot? If something died, it’ll release a ton of ammonia which can absolutely overpower your cycle and spike your ammonia.
Too much waste - You need to vacuum your substrate and clean your filter every so often. If you don’t, all the brown gunk stuck in your substrate and filter slowly decays and releases ammonia, which can eventually overpower your cycle. Overfeeding can also cause this issue, so if you find yourself needing to clean up very often try feeding less.
Your filter is too weak - Especially if you have a lot of stock, you should always try to have a filter for twice your tank size. A 10g tank should ideally have a filter meant for a 20g tank or larger. Filters that are too small won’t be able to keep up with big bioloads as easily, and they get clogged more easily.
Something crashed your cycle - If you’ve ruled out the other issues and you’re still having major issues, something may have crashed your cycle. Perhaps you got some cleaning product in your tank, or soap, or maybe your temperature or pH just went to an extreme for a while. No matter the case, if this happened you need to first clean everything in your tank to ensure you won’t have a repeat, then do daily water changes as you wait for your cycle to restart. Churning up your substrate will speed this along.
The Fix
So the actual truth is that there is no real instant fix for ammonia in your tank. The fact is, to keep a tank ammonia free, you’ll need a stable cycle, which only comes with time (and strong filtration). Luckily, however, there are a few ways to speed things up!
Short term
In the short term, if you have ammonia in your tank and need to keep your fish alive, there’s only one solution: Do a damn water change. Change out around 80% of the water, and fill it up with dechlorinated, clean water.
Using ammonia detoxifiers isn’t a valid solution. While these may work in the very short term, they’re not useful to rely on and not generally helpful for the fish. They convert toxic ammonia (NH3) to ammonium (NH4+), which is less toxic than ammonia, but is still relatively toxic to the fish. The bigger issue is that ammonium can readily convert back to ammonia, especially in environments with a pH above 7. All in all, this means they’re okay for a very immediate solution, but shouldn’t be relied upon to keep your fish safe. Just do a water change.
Adding an oxygen bubbler with an air pump is another great short term solution. The bacteria in your filter is aerobic, meaning it needs oxygen to thrive, so adding more oxygen to the tank will help the cycle speed up and help ammonia break down.
Long Term - The permanent solution
The easiest way to get more bacteria in your filter to stabilize your tank is, very simply, literally adding more bacteria. Bottled bacteria such as API Quick Start does help, but the best solution is to use dirty filter media from another tank. If you have any other aquariums, simply take the filter media out of the filter of the other tank and squeeze it right into the water of the problematic tank. The gunk is packed full of bacteria, and it will quickly colonize in your filter and speed up your cycle.
We also offer mail-order fully cycled filter media, which you can just add directly to your filter or tank and dramatically speed up your cycle! It’s perfect for helping cycle new tanks or stabilize mature tanks. You can get some here!
Other than adding more bacteria, the solution is to simply allow your filter to cycle.
Ensure your filter has plenty of filter media and places for bacteria to colonize
Ensure your tank has deep substrate- the deeper the substrate, the more room for bacteria and the more stable your tank will be
Ensure your filter and tank has ample oxygen and water flow
Consider doing a fish-in cycle such as our One Week Cycle
