Ammonia test - chemistry question

[Qrystal]

OK, I've got a question that's chemistry related, and I realize it may be best to ask my friends in Chemistry (as a physics major, they basically "live right next door"), but I'll pose the question here first (because it's the Sunday before Reading Week, and nobody will be on campus for the next week).

I've been working on a fishless cycle, and one day I decided to "recalibrate my interpretation" of the colour scale for the ammonia measurement ... that is to say, I wanted to see what the highest concentration (8ppm) would look like. I've got the Aquarium Pharmaceuticals Freshwater Master Test Kit, and the ammonia scale has 0, 0.25, 0.5, 1.0, 2.0, 4.0, and 8.0 ppm divisions. The 2.0, 4.0 and 8.0 colours go from medium to dark green, and they're not very easy to distinguish from each other.

So I tested the pure ammonia, which is a 5% solution (50000 parts per million). The test showed ZERO!!! I thought for some reason that the test would always show the max value if the ammonia concentration was above the max level on the scale, but is it possible that's not true? Maybe too much ammonia reacts with the reagents too quickly or something, and the colour doesn't appear as expected?

I am going to experiment with different dilution levels to see what happens, but in case someone here interjects with some experience before I'm done, I would be glad for the interruption. Thanks in advance.....

~Qrystal~

 

[FroggyFox]

wow interesting. Did you try the test twice and make sure you used both solutions (assuming that is the type of test you have)? I've accidentally done twice the amount from the same bottle or forgotten the 2nd bottle and come up with weird things. Maybe that extreme of an amount throws everything out of whack? I would have said that it turned dark green.

Generally the test kits we use for aquarium stuff are really just litmus tests...if the result is dark green, there's too much ammonia for your fish to live healthy lives, if its yellow you know that ammonia isn't the issue. (ahem...unless you have a 5% ammonia solution in your tank apparantly haha) The reason that the fishless cycle says 5ppm is really just a number in the middle of that color scale so that you can see its not WAY dark and off the charts, but that you can see when it starts disappearing etc.

I'm sure nothing I said helped your actual question I'd be interested to hear if you get any logical answers on that one. You might even contact the kit manufacturer to see if they have an explanation?

 

[Qrystal]

Heh, thanks for the response.

Yes, I thought I probably just used twice from the same bottle or just plain forgot the second, and I DID try again --- but I got the same result.

So I bought a new kit, different company (TetraTest) and the same thing happened. I would really like to know what's going on! I guess it's time to crack out the chemistry books, start counting moles! I'm sure it will be fun, but I'm also sure I don't have the time to do it immediately.

So I decided to test something else: I added the ammonia to the tank in the perscribed quantity, waited a bit, and measured the levels. I got a nice healthy green, as I was supposed to, so I think I've confirmed that the ammonia has to be dilute enough or else the results won't make sense. Maybe someday (when my ammonia levels are a steady zero, perhaps) I'll prepare some test solutions and find out what concentration of ammonia overwhelms the tests. (I'll post results here.)

I'm keen on hearing other people's thoughts on this, especially if anyone has done what I'm wanting to do and can spare me the agony --errr fun!--- of doing it myself!

 

[Lotus]

I guess you're getting a false negative from the test kit. Its range is only zero to 8ppm, so it's not designed to measure much higher than that. In most aquarium circumstances, you shouldn't really get higher than that (unless you leave something dead and rotten in an uncycled tank for a few days). At 8ppm you would probably have a tankful of dead fish, and it would be a little late to test.

Also, you should remember that hobbyist test kits aren't anywhere near lab-grade test kits, for the most part. A "ballpark" figure is about the best you can hope for.

 

[nicolleen]

Hi,

what kind of ammonia-solution is it, and how old is it? could it be that there is no ammonia left in your solution (only nitrate)?

lg
niki

 

[FroggyFox]

Its a normal water/ammonia solution, hopefully not much else in there otherwise it'd be toxic for the fish once the tank finally cycled. She said that in normal testing she got the right green colorations...so she's not accidentally testing only water etc...

 

[Qrystal]

what kind of ammonia-solution is it...?

I am suspecting the solution is of ammonium hydroxide, mostly because of the way the pH jumps soon after adding it to the tank.

Idea: test the pH of the ammonia solution.
Result: pH > 8.8 (off the chart actually, the darkest colour on the chart is not as purple as the result I got)

Interesting, but it doesn't tell me anything

I haven't yet asked anyone in the chemistry department.... hmmm.....

Oh well

 

[wonghee76]

hai...

1.because i m from asian country, i don quite sure ur ammonia source u r using?acually v can calcualte the moles as u said and i wish to help to calculate but i need to know the chemical name and dilution u make (?g/?Liter). second most our household product are industry grade which mean they are not that pure as for the lab used grade.

2. u are using AP fresh water master test kit, may i know it is nessler reagent or salicylate reagent? it is writen on the label attach? but for both the reagent, higher ppm then the color indicator attach will gave darker colour. there must be something wrong with your source that it gave zero ppm result.
if ur source of ammonia is correct, u no need to dilute the tester or the source to be able to read the ammonia/ammonium level.

3. there were a lots diferent between ammonia and ammonium chemically and it is the ammonia that kill our fish.the higher the ph the more ammonium were in the ammonia phase.

*laughingc i hope this may help abit

Hee

 

[crissy7399]

Can I ask another question??

I have been testing my water every other day,(have 5 tiger barbs- 2 weeks in 46 gallon, cycling) and I still can't tell if my yellow color .00 is getting close to the yellow/green color .25. If your in natural light it looks slightly different too.

My question is, at what "color" should I be concerned about my fish? I found the following information on a website.

PH____68F___77F
6.5___15.4___11.1
7.0____5.0____3.6
7.5____1.6____1.2
8.0_____.5_____.4
8.5_____.2_____.1


The figures are to determine what amount of ammonia is too high for the fish. Are these figures reasonable? If so, my tank is around 7.8-8.0 PH and 75F, which would make it close to .4, and then if it ever reaches that, I guess I'll just do a 20% water change?

Any comments would be great!

FYI: I think calling the manufacturer on those tests is a very good idea.

 

[Qrystal]

(Hmm, for some reason this thread didn't show up as updated in my User CP ... ...sorry I took so long getting back to ya.)

Anyways, thanks for replying Hee... to answer your questions:

1. The ammonia source is a product called Goldex, and I read in another forum from someone who contacted the company and it was verified that the mixture was 5% ammonia and pure water with no additives. I tested the household ammonia straight from the bottle, and I also tried diluting it with half tap water, and both times got a zero result.

I read elsewhere (http://badmanstropicalfish.com/articles/article14.html) that ammonia can be added to water either in the form of ammonium chloride or ammonium hydroxide, and I suspect that mine was made via the latter ingredient because it was extremely basic and my pH always jumped quite high after I added the formula to the tank. The link above also suggested using granular ammonium chloride because it won't have that effect, and because the amounts can be more regulated, but I was silly and didn't ask in my chemistry department for "the good stuff". I know better now

2. My test uses the salicylate reagent.

And yeah, I thought as well that I should've gotten the darkest colour, and yet I got a zero reading. But when I added it to the tank in the appropriate amount (~10-11 mL of 5% solution into 109.8L) I got a reading of 4ppm on the chart.

3. The solution is basic, so the dissolved ammonia should not be the undetectable ammonium, right?

crissy: since you're cycling, you should expect to see your ammonia go up. I just don't know the details about cycling with fish... like whether you're supposed to do water changes or not (I just know you shouldn't in a fishless cycle). I do know you need the ammonia to get high so your bacteria will have lots to eat, and eventually they'll start flourishing and get working on reducing the ammonia levels. Then your nitrites will get up to "dangerous" levels (this is why you cycle using hardy fish), and the bacteria that eats that will have the chance to flourish, and then just when you're starting to worry, the nitrite level will drop by about half one day, and to zero the next, and hopefully stay stable until you add some more fish. Anyone else wanna add something to that? (P.S. It's not usually a good idea to ask a new question in someone else's thread; people may be ignoring my thread because I've asked a rather obscure question, and so not too many people are likely to see what you're asking.)

 

[crissy7399]

Thanks Qrystal,

ya, should have done another thread, thanks for the input though

 

[wonghee76]

hai...

sorry that i not quite familier with ur country household brand

anyway...if i not mistaken, u means tat ur source is 5% ammonium salt in solution means that is 5g of ammonium salt in every liter water that is 5000ppm, right? when u r using 10 ml of the 5000ppm ammonium salt in 10 liter water(sorry, u din mention ur water testing valumn), it dilute to be 5ppm , so ur tester will gave the reasult of 4ppm that is more close , is this reasonable?

ok.assume that ur source is ammonium hydroxide that can increase ur ph value, then at 5000ppm, the pH should b very high, that means the pH is very alkaline, and in this case, the ammonium salt is in the ammonia form as the ammonium will release the H to the water.

pH 6 7 8 9 10 11
% NH3 0 1 4 25 78 96
% NH4 100 99 96 75 22 4

as can c from the table above, if the pH is more alkaline, the ammonium salt like to be in ammonia form. may this explain the reason no detection of color on pure source of 5% ammonium salt? as the salicylate tester surpose to detect ammonium and not ammonia.

may ur case be explain like this:
1.when the source of 5%, assume that the pH is 11 or more, all teh ammonium salt were in ammonia stage, that gave no result when tested.
but the label
2.when the source of 5% dilute in 10 Liter of water,it become only 5ppm and the pH decrease to pH 8 , then 96% of the ammonium salt were in ammonium stage.

hope u get wat i means.

the salicylate reagent from AP declear that they can detect both ammonia and ammonium, in this case, mayb the product fail to detect the ammonia in high concentration? try to test ur source with nessler reagent and observed is there any colur indicate? if it do....means my teory is correct *celebrate



this is fun...

nice to meet u alll....


have a nice day

Hee

 

[Qrystal]

I like your analysis Hee, thanks for the input. That actually makes a whole lot of sense, and I am almost ready to conclude that this test can't measure ammonium. I am considering getting something to lower pH, add it to the ammonia solution, and test again. But it might be easier to just find myself a nessler reagent, I just have to figure out who to ask

Perhaps the same colour chart is distributed with both their salicylate and nassler based reagents... and in the case of the salicylate test, the NH4+ part is a lie/mistake (which wouldn't be surprising since your version of this same test claimed that 2 30mL bottles could give 135 tests!)

I have another test (brand:TetraTest) but it also gave zero when I measured the ammonia solution from the bottle. I suspect it is also salicylate, because upon looking up nessler (http://en.wikipedia.org/wiki/Nessler's_reagent) I found that the nessler reagent contains potassium, and this test warns about only the following ingredients: (bottle #2) phenol (carbolic acid), sodium nitroprusside dihydrate, isopropanol, (bottle #3) lithium hydroxide, sodium hypochlorite solution. It doesn't say anything about what's in bottle #1, though. From the sounds of it though, the nessler reagent is a single ingredient that turns yellow in the presence of ammonia/um, and so this likely isn't it.

Small corrections/notes that don't affect your analysis:
- 5% solution means 50 g in 1 L, so 50000ppm.
- My tank is 29G = 109.8L, which means 10.98 mL of solution is needed to make 5ppm.

Again, thanks for the help... and yes, this is fun, isn't it? *laughingc