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Skeptical about API Ammonia test kit?

7K views 11 replies 11 participants last post by  sbo80 
#1 ·
Last month, I bought the master test kit, and the ammonia constantly read out 0.25 ppm. This lead me to constantly change water. However, today, I got fed up with the reading, and decided to test other waters, since I've never seen 0 ppm ammonia ever. I tested it in my remineralized distilled water, and it reads out 0.25 ppm. Ok, it might be contaminated. How about my distilled water I use to top off? It reads 0.25 ppm. Ok, let me open up a brand new water bottle I'll drink from later. It reads 0.25 ppm. Has anyone ever seen 0 ppm for ammonia? During my tank cycling, the ammonia went up to like 0.5 ppm, then a week later the nitrite went up to 2.0 ppm, and then nitrate went up to 20 ppm a week later. Today, the nitrate and nitrite are at 0, but the ammonia is still at that cursed 0.25 ppm, no matter what.

Can I just assume this is just error? (My tank is heavily planted (along with duckweed) with about 20 snails, if this makes a difference)
 
#3 ·
Just a guess that you need to rinse out both the test tube and the cap a few times before testing since you've got some ammonia reading despite different water sources.
 
#6 ·
Nor can most 'ammonia' test kits. I think the Seachem kit may be the only hobbyist test kit that can differentiate between ammonia (NH3) and ammonium (NH4).

Anon
 
#5 ·
I have gotten 0 ppm on my API ammonia test only when testing my tap water and distilled water. Otherwise, the test ALWAYS shows 0.25 ppm ammonia whenever I have tested any of my tanks, whether they are brand new just set up or have been cycled and running for years.

I think if there is any amount of ammonia whatsoever in the water it will show 0.25. There will always be some amount of ammonia since there needs to be something to feed the bacteria that eats the ammonia.

I don't worry about the test reading now unless it goes darker, to 0.50 ppm or more.

Sent from my moto z4 using Tapatalk
 
#8 ·
Your skepticism is justified: the API kit always reads .25 (at least, mine always did). The Seachem test is a pain to administer, but I like their "Ammonia Alert" tags for my QT. I found that the Salifert kit does distinquish between zero and some total ammonia, and is easy to use. I wouldn't worry about the "free" (NH3) vs total ammonia. Just focus on total ammonia, which is all that the Salifert and API kits do. If your pH is above ~7, then the total ammonia is free ammonia (NH3) and is the dangerous type. If your pH is below ~7, then it is in the safer ammonium (NH4) form.
 
#9 ·
My API test kit always reports somewhere between 0 and 0.25 for water that should be ammonia free (untreated tap water). I have a simple method for determining if my aquarium has unhealthy ammonia levels.

When testing for ammonia I run two tests: one with tank water and one with untreated tap water.

I compare the two tests.

If the tank water shows equal ammonia to tap water, the tank water has no ammonia.

If the tank water shows more ammonia than tap water, I know there is an ammonia problem.
 
#12 ·
I've seen the same thing. It never really looks "zero". But I test regularly and I always see exactly the same thing, so I don't worry about the number and only check that it's just not changed. I have a 120gal and I can change out 50 gallons of RO and it'll still read ".25". They're not precise things anyway. There's other threads that complain about the inaccuracy/difficulty of the API Nitrate tests too. Above about 15 I find it very difficult to perceive if it's 30 or 80.
 
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