Ammonia and Ammonium in the Aquarium

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Ammonia is a nitrogen based compound that is extremely toxic even at very low concentrations. Most aquarium owners are told to keep ammonia concentrations at 0 (undetectable by test kits) and for good reasons. Concentrations as low as .01 mg/L (ppm) can reduce the fitness of your fish, although ammonia toxicity is largely species dependent. Some fish can tolerate higher levels while others prove to be more sensitive.

Ammonia is generated by fish waste and the breakdown of organic molecules by bacteria in the aquarium. It exists in an equilibrium with its non-toxic counter part ammonium (NH3/NH4+).The relative amount of each form will be dependent of the pH at any given time.
When the pH is 9.25 there will always be NH3 and NH4+ in equal amounts (1:1). Every time we move 1 full unit of pH there will be a 10 fold increase or decrease of this ratio. If the pH of your aquarium is 8.25 there will be 10x more NH4+ than NH3. If the pH is 7.25 there will be another 10 fold increase resulting in 100x more NH4+ than NH3.

This means that ammonia toxicity increases and deceases with pH. Aquariums with a higher pH will thus have more nitrogen in the toxic NH3 form and vice verse.
When plants, algae and microorganisms remove ammonium from the water column, the equilibrium between NH3/NH4+ must be restored, thus NH3 molecules will protonate and form NH4+. This action will in turn reduce the amount in the NH3 form and act to reduce the toxic NH3 load.

[Guppy_Girl]

9 years later and this video is still the best one on the subject.

[billg.]

I'm a retired biology teacher and have been doing fish ( both koi ponding and tropicals ) for decades. This YouTube video is THE finest lesson on NH3 and NH4 as it relates to pH. So many people out there are needlessly worrying about their aquariums, doing chemical additions, and water changes frantically when they really need not worry. One should test for both Total Ammonia (NH3 and NH4) and especially for NH3 alone. Try getting the Seachem product that does both tests. The only result that should cause alarm is the test for NH3 which is the fish killer. Thanks much Aquapros for explaining it so nicely and scientifically. Even I had to watch it a couple of times to take it in, but it is absolutely critical that all fish fanciers watch and learn. The science explained is black and white and the job they did was easy to understand. The pH of the tank/pond is THE determining factor in how things work regarding ammonia in its various states. Other factors apply in a tank ecosystem, but without getting pH levels ideal, the ammonia issue will rear its ugly head.  
While water changes are a good thing done in moderation, massive numerous changes can harm fish too with temperature issues, pH change issues, and the like. I wonder how many people blame ammonia for fish illness or death when, in fact, it was something else that caused problems.

I have hard well water with a high pH of 8. Adding RO water to it greatly reduced the pH to the 7.4 ish range which is about what I'd like, if not my gradually lowering it to 7.2 or so. In doing so, my ratios of NH3 to NH4 will go in my favor as the bad stuff (NH3)will go down and the good/neutral (NH4) will go up. Simple concept to grasp if one is willing to put forth the effort to learn and apply.
Lastly, remember that even my better NH3 actual results will be hidden by a Total Test for ammonia which reads high as it is including both the NH3 ..and..the NH4. The NH3 test alone will tell me the actual dangers to my fish. A higher level Total test reading may be perfectly ok for the safety of the fish, but people often, meaning to do well, actually shock their fish in other and or massive numerous water changes.
This the only reasonable test kit I found capable of testing the NH3
Again, thanks to the people at Aquapros😀

[BioHaj]

I spent hours on Polish websites trying to find the proper explanation of NH3 vs NH4, and couldn't, people mix these two up. The amount of stress that I had when I saw that I have loads of NH4 in my fishtank was unbelievable. This video finally made me realize the difference and that with my pH - 6, 05, having 0, 5mgl of NH4+ is completely fine.

[salvolondon]

Ph and temperature too plays a role . Lower temperature convert ammonia in ammonium

[WaterFish]

Great video I didn't know about the 9.25 ph 1:1 ratio! Still learning new stuff!

[Confused_Hippie]

Can't believe I had to dig for this after searching "unioized toxic ammonia" Awesome video!

[CaptainSavageAquatics]

Thank you for the video! It was very informative!

[bubblerings]

Maybe add another post of this called The Truth About Ammonia in Aquariums.
This is important info.
Hope more people will see it. Liked! 🍻🎯
(I even searched for this topic, Ammonia Aquarium PH... but found this vid by accident, later)

[theleo]

Can you talk about water changes and tap water that has ammonia in it.

[diegosandovalmiamifl]

Thanks for all your videos. Question my tap water has almost .50 ppm amonia chloramine, my tank is reducing but not all of it. And prime works for like 24 hrs. RO water is not an option for me. I was trying to set up a cichlid tank but watching your video of amonia and ph, would be worst for higher ph fish like cichlids? My current tank is plantes tank some fish died (3) and i was doing alot of water changes but my problem was my tap water. Thanks for your feedback.

[MarcassCarcass]

So is NH3 considered "free ammonia" because it hasn't picked up a proton or hydrogen ion?

[egxv]

Can someone help me? I just finished cycling my tank (about 7 weeks of cycling). Its a 5.5 gallon tank and I have live plants in the tank. Yesterday I tested my tank and it showed 0 ammonia, 0 nitrites and about 10 nitrates. I added my new Betta today. Obviously being his first day he is stressed out, looks a bit pale and just stays in one spot, at the very top by the surface or behind one of my plants, very little swimming around. I decided to test my tank today and it now shows .25 ammonia, 0 nitrites and a little less than 5.00 nitrate. I’m pretty sure the nitrates went down because I added some of my aquarium water to the Betta cup while I was acclimating him and had to replace the water with tap water. The thing I don’t understand is why my ammonia went up. Is it because I just added a fish? I’ve tested my tap water and it’s 0 ammonia and I always use prime when adding new water.

[richardblase]

The article is good but complicated for new koi owners

[MrPropnash]

once ammonium increases the pH goes low, not the other way around.correct?

[rastime]

Hi Well, sorry, but I am not so conserned if ph modifies the water or how ammonia is produced. It would be more necessary to know the details about what specific level of nh3 or both nh3/nh4+ is the the limit or the minimum that our fish needs since there are fishes more sensitive to ammonia than others. How can we do the calculations.

[MRRoyan]

Hi, would you like to give me the reference how to convert the value of NH4+ to NH3 if the value of NH4+ is known?

[MRRoyan]

Due to reference that I was looking for, I've just found about how to calculate un-ionized ammonia from TAN (Total Ammonia Nitrogen/ [NH4+ + NH3]). So, how can we formulating an equation for converting NH4+ to NH3 (not from TAN)?

[lucohen]

thanks for the video I think I can apply this to whats going on my tank, my 55gal ph is 6.4 to 6.6 and nitrates and nitrite is zero, my ammonia reading is 0.50bpm, should I worry is been like that for weeks and nothing or water changes lowers my reading. all fish are doing fine, I have a total of 26 small fishes andn I feed ones day, I have spent hundreds buying products and nothing lowers it less than 0.50.. what can I do should I worry?

[TheBSideDJ]

the question is : which form is the most toxic for fish ?? I've been told that a lower pH is less toxic, so if NH3 is lower with low pH, it means that NH3 is more toxic then NH4 ?

[jillmurph]

Why are so many test kits the combined NH3/NH4+ test? I did find one from Seachem that singles out the NH3 but seems to be less common.