False Positive On API Ammonia Test?

What light are you reading it under?
Fluorescent tubes, including energy saving bulbs, are well known for causing a false positive. Daylight, old fashioned incandescent bulbs and halogen bulbs are better. But a lot of people still report this greenish tinge even in daylight. However, a trace of ammonia is unlikely to cause problems even for the most sensitive fish.

Ammonia exists in 2 forms in water. The bulk of it is in the ammonium form (NH₄⁺) but some is in the ammonia form (NH₃). The ammonium form is much less toxic than the ammonia form. But test kits measure both of them, and we don't know from the test kit just how much is in the more toxic form. The amount of each varies with both the temperature and pH.
At 25^oC and pH 7.5, even an ammonia+ammonium reading of 1.0 contains a safe amount of the toxic form.

The highest safe level of the toxic form is 0.02ppm. Here is an ammonia calculator. Just enter your test reading, temp and pH to calculate. If the result is lower than 0.02 there is no need to worry.



And yes, there are better test kits than API, but more expensive. The make that is usually quoted is Salifert.

hi, i have seen that a number of people are saying the same thing.
its possibly down to variations in the printing process of the test card  and different peoples color perception.
lighting can affect it too.
as long as all the other tests look ok there shouldnt be much of a problem.
after another month into the cycle i think i will look for a more accurate ammonia only test.

I agree with the nitrate colours I find it nearly impossible to know what my nitrate is and I too have high nitrates normally.  I can't comment on the other tests though I'm afraid

Yeah the API nitrate colours are a pain around the 40-80ppm range (which is where mine tends to read). I do find I get a good strong yellow with the ammonia test though.

That's a good water, Sue. My water company quotes Nitrates between 24.5 and 40.9. I use Seachem Prime to remove Chlorine and it is meant to detoxify Nitrates, but I wonder how does it work in practice. API recommends Nitra-zorb to remove Nitrates so may look into this also.

Thanks for pointing that out Sue. I feel a bit uneasy about using it as I don't want to mess about with the ammonia/nitrite/bacteria balance. Ideally I would just like to remove nitrate. I had a look around and a few people mention Pozzani Aquarium Nitrate Removal Filter, which works by removing Nitrate from tap water before you add it to the tank. People who use it report that it can get 40ppm down to zero. It's a bit pricey though, at about £40 including shipping and requires cartridge changes at £16, but some say the cartridge lasts several months.

Thanks for the tip Chris! So that would mean you are adding nitrates by doing water changes more often than not and plants are using it up! That's really good, what are the fast growing ones you have? I don't have many plants comparing to the 180l volume of water. I had the tank less than two weeks, so plants will grow in time.

Just did a nitrate test of tank water (on the left) and tap water (on the right) and they look the identical, somewhere between 40 and 80ppm, I can't tell which. Both around the same mark so I don't think water change will improve anything. So frustrating.

That looks the same as mine.  Very frustrating!!

Did a bit more research and found Nitratex http://www.jbl.de/en/aquatics-freshwater-products/detail/2427/jbl-nitratex , which I think can be put into the regular filter in the tank. Or you could put it into a spare filter and run your tap water through it and remove nitrates before water change. I think I'm going to get it and let you know how I get on.

Thanks for looking it up! When you say it works by ion exchange it sounds like a bad thing :-o Do you think that I'll get rid of nitrates only to introduce something else I may not want in my tank? Yes, I've seen bionitratex, but as it takes weeks for bacteria to establish itself I haven't considered it. Maybe I should.