Lets Talk About Ammonium

[Miss Wiggle]

Right, been wondering about ammonium a bit and got a few questions, just wanted to prompt a bit of debate to improve my understanding.

so products like ammo lock say that they deal with ammonia in the tank, we know what they do is convert it to ammonium which can still be used by the filter bacteria so the tank still cycles and it's less harmful to fish.

so questions

1 - is ammonium harmful to fish at all, is it just 'less toxic' to fish than ammonia or is it 'non-toxic'. If it is still toxic then at what concentrations to we need to be concerned?

2 - do the filter bacteria prefer ammonia or ammonium as a 'food' source, will they readily take either, if for example you were doing a fish-in cycle and using ammo-lock to control the ammonia is the cycle likely to take longer or anything like that. What effect does it have?

3 - what actually is ammonium, i assume it's some chemical compound made up of ammonia and something else, so what is it?

any other exciting and useful info on ammonium I'd love to hear it.

Thanks

 

[backtotropical]

Hi MW,

Interesting thread. I'll be interested to see how it develops, and i'll start.

1) I believe that ammonium is still toxic, only to a lesser degree. I can't prove that scientifically though, so maybe one of our scientists can? I'm not sure at what levels we should start to be concerned.

2) Again, i know that the bio-filters in our tanks can use ammonia and ammonium, but i'm not sure about their preference.

3) This one i can answer in a bit more detail. Ammonia is NH3 which is basically 1 part nitrogen and 3 parts hydrogen. Ammonium is NH4 which equates to 1 part nitrogen and 4 parts hydrogen. The extra hydrogen molecule is the difference.

Hope this helps a bit, and i'm sure one of our more science minded guys will be along soon to tear my answer to shreds.

Cheers

BTT

 

[Miss Wiggle]

excellent, thanks for that BTT.

Thats one question off my list then at least!

Oh the other thing I meant to ask, I've heard all sorts of things about testing for ammonia/ammonium and the test kits giving false readings. so whats the reality, do our kits test for both, is there any way of telling how much ammonia and how much ammonium we have or anything like that?

 

[rabbut]

The ammonia and ammonium levels change proportionately to each other, according to the pH. Most kits I have used test for total ammonia, (NH3 and NH4 together) but some do test ammonia (NH3) only. Bignose (I think) has a post decribing the proportion of ammonia to ammonium according to pH somewhere... I cannot help with accuracy of test kits realy, sorry

All the best
Rabbut

 

[xxBarneyxx]

Cant add anything unfortunately but an excellent topic to bring up! Really interested to see what is said.

Edit: Link to the excellent post the Bignose has already written. Still reading but think it does cover a lot of this.
http/www.fishforums.net/index.php?showtopic=154313&

 

[Bignose]

In answer to part 1) the simple truth is that if there is ammonium, there is ammonia, too. Nature doesn't allow one to exist without the other. Any individual molecule is constantly changing from ammonia, picking up a stray H+ ion and then becoming ammonium, then that ammonium sheds a hydrogen ion H+, and becomes an ammonia again, repeat over and over and over. The split of how much is in each species is given in my article linked above.

So, the thing is that there isn't only a "dangerous level of ammonium" because once there is some ammonium, there will be some ammonia, and it is that concentration of ammonia that is dangerous.

Ammonium itself too bad. It is most typically the form that the fish excretes out of it's body via ion-exchange. That is, the fish's body releases an NH4+ ion and then has to find another + ion to pick up to maintain a charge balance. Na+ is common. Or, the fish can release 2 NH4+ and then pick up 1 Ca++ which has a +2 charge.

2) I am pretty sure the bacteria convert the ammonia or ammonium into whatever form they prefer. I actually don't know which they use. I'm not sure if the bacteria use ammonia and kick off the H+ into the water and excrete the nitrite ion (NO2-) or if the bacteria use ammonium and excrete nitrous acid (HNO2).

3) BTT is pretty good. Just remember that NH4+ is an ion with a +1 charge. That charge is an important influence on its chemistry, so most chemists do put the + on the ion to make its charge very clear.

 

[Miss Wiggle]

hmmmmm so if any ammonia in our tanks is kind of fluctuating between ammonia and ammonium then what do products like ammo lock actually do and do they work?

So I can see that they could add this extra charge to the ammonia and convert it to ammonium, do they do something to lock it into it's ammonium form or would it continue to fluctuate between the two depending on things like the pH? If they continue to fluctuate then really can we say that it actually works or not?!

 

[Schmill]

I can't answer any of the questions directly, but after doing some searching myself, the following three articles seem to contain a lot of interesting information on this.

[URL="http/www.extension.iastate.edu/CropNews/2008/0421JohnSawyer.htm"]http/www.extension.iastate.edu/CropNews/...1JohnSawyer.htm[/URL]
[URL="http/edis.ifas.ufl.edu/FA031"]http/edis.ifas.ufl.edu/FA031[/URL]
[URL="http/aquabase.wordpress.com/2007/05/03/ammoniaammonium/"]http/aquabase.wordpress.com/2007/05/03/ammoniaammonium/[/URL]

Of most interest to me was the third article.

This seems to differentiate between 'free' ammonia and ammonium, and 'locked' ammonia and ammonium.
In summary of the points it seems that no (?) ammonia tests can actually differentiate between ammonia and ammonium.
There are 2 types of test, a "Nessler" and a "Salicylate".
The "Nessler" will detect the total ammonia in the water, that is the free ammonia, the free ammonium, the locked ammonia, and the locked ammonium.
However a "Salicylate" test will detect only the 'free' ammonia and ammonium.

So perhaps we aren't quite understanding how things like 'Ammo-Lock' actually work?
The only mention of this I can find is in the 3rd document which seems to say that they contain Formaldehyde, which chemically bonds to the ammonia to 'lock' it.

So...

Does this mean that 'ammo-lock' et al DON'T actually convert the ammonia to ammonium?
Which sort of test does the API Master Test Kit contain, Nessler or Salicylate?

Also from the 2nd document comes the table below, which apparently shows the fraction of unionized ammonia in aqueous solution at different pH values and temperatures.

Fraction of unionized ammonia in aqueous solution at different pH values and temperatures. Calculated from data in Emmerson et al. (1975). To calculate the amount of unionized ammonia present, the Total Ammonia Nitrogen (TAN) must be multiplied by the appropriate factor selected from this table using the pH and temperature from your water sample.

 

[aaronnorth]

does ammonium & ammonia form covelant bonds?

I can see ammonia doing it as N needs 3 more electrons so 3 Hydrogens fill the outer shell, but how does ammonium do it?

Thanks

 

[Bignose]

does ammonium & ammonia form covelant bonds?

I can see ammonia doing it as N needs 3 more electrons so 3 Hydrogens fill the outer shell, but how does ammonium do it?

Thanks

Ammonia is neutral, but the molecule can accept an H+ without too much of an energy barrier to overcome. Then the ammonium can participate in ionic bonding.

 

[Bignose]

Also from the 2nd document comes the table below, which apparently shows the fraction of unionized ammonia in aqueous solution at different pH values and temperatures.

Oh gee, if only that information was available before and maybe even had been posted on this forum say over 2 years ago?

Oh wait, it has! A link to that thread was even posted in this thread! http/www.fishforums.net/index.php?showtopic=154313&

I kid because I love.

It is interesting that the numbers, while close, still have some significant differences. I did use a more recent article (1995 versus 1975) for the source material for the equilibrium constant, but I don't think that 20 years would have made that much of a difference. Ammonia has been studied extensively for quite a long time. I'll have to look into this a little more closely...

 

[Schmill]

Oh, I'm sorry, I didn't realise it had been discussed before, this was my first time

I am interested in seeing where this goes though. Just for my own curiosity, how was it discovered / decided that things like Ammo-Lock converted the ammonia to ammonium? Also if that is the case, then do you have any idea what that article is on about when they talked about 'free' ammonia and ammonium, and 'locked' ammonia and ammonium, (if we are classing 'locked' ammonia as ammonium?)
Or do I have the wrong end of the the wrong stick?

 

[Schmill]

In answer to one of my own questions, the API Master Test Kit test for Ammonia is a Salicylate type test, which according to those articals above will only detect the 'free' ammonia and ammonium, and not the 'locked' types.

This is of a concern to me, because if the 'Ammo-lock' products are doing this other kind of 'locking' to the ammonia and ammonium, and not just converting the ammonia TO ammonium, then when we've told people who have high ammonia readings whilst using ammo-lock that everything is ok and it's just the 'ammonium' that they are detecting, we might be wrong (if the kits aren't ACTUALLY detecting locked ammonia at all)...

 

[Miss Wiggle]

does ammonium & ammonia form covelant bonds?

I can see ammonia doing it as N needs 3 more electrons so 3 Hydrogens fill the outer shell, but how does ammonium do it?

Thanks

does ammonium & ammonia form covelant bonds?

I can see ammonia doing it as N needs 3 more electrons so 3 Hydrogens fill the outer shell, but how does ammonium do it?

Thanks

Ammonia is neutral, but the molecule can accept an H+ without too much of an energy barrier to overcome. Then the ammonium can participate in ionic bonding.

ok excuse my complete ignorance please...... here to learn!

can you explain what you mean by covelent bonds and ionic bonding please?

 

[aaronnorth]

covelant bonds is when at least 2 atoms share electrons. electrons are situated on 'shells'. They can have 2 electrons on 1st shell, then 8 on second, then 8 on 3rd (doesnt usually go past this point)

so nitrogen has a total of 7 electrons. 2 fill the first shell which means it needs a further 3 electrons to fill the outer shell. by sharing electrons with hydrogen it can do so, and it makes the compound safer.

Meanwhile hydrogen has 1 electron on first shell, so it shares 1 electron with nitrogen to have 2 to complete a shell.



This takes place with 2 non-metals



Ioinc bonding is when atoms gain or lose electrons, this takes place with a metal, and a non metal.