ammonia tester faulty?

[chris brown]

I have just noticed my tank is getting ammonia after i have just done a 50% water change and cleaned the filters i dont no y and none of the fish are acting odd. I am going to take some water into my lfs to get them to test it today.
the tank has been running for about 1 year ish and i havnt had any trouble with it b4 but saying that i have only recently started testing water quality and am pretty new to it so could be me reading it wrong
the tester is a mardel and reads 0.02 (caution)

have just tested everything myself and got this
NO3 0, NO2 0,(api test strips),
ph 6.6(mardel)

has anyone had trouble with these testers?

[UVvis]

Going into the water chemistry aspect.At a pH of 6.6 (and lower) you are going to have more of the NH4+ and less of the toxic NH3. I'm not sure if the reader is NH3 specific or not as I'm not familiar with what methodology it uses for analysis.

Depending on your source water and the presence of chloramines (intentional or disinfection byproducts off of standard water chlorination), you can get a little carryover of NH3(4) in your source water.

If you performed maintenance on your filtration you may have slightly harmed part of your biological filtration. Luckily bacterial populations usually bounce back fast if they are already seeded well.

I'd keep an eye on your reader and see what happens. I'm always skeptical of any result I get on almost any instrument, but you have to trust something at some point.

[chris brown]

thanks i went to to lfs yesterday and they tested it and it was all ok so went home and took the old tester out put it in a cup of tap water and it didnt move so must be stuffed
as for the ph it was done with the same brand of tester as the ammonia (mardel which i now dont trust) so have brought a aqua master ph tester and have just tested and got 7.2 so my conclusion is mardel is crap

as for chloramines is that the stuff they put in tap water thats ment to be good for teeth? or something cos yes they do do that here

[UVvis]

as for chloramines is that the stuff they put in tap water thats ment to be good for teeth? or something cos yes they do do that here

Negative.

Many water treatment plants will use floride for the teeth.

Chloramines are basically ammonia with chlorine in the place of hydrogen atoms (NH3 versus NH2Cl. It is used as it is a longer lasting disinfectant than just chlorine alone. Many of the chlorine neutralizers will use thiosulfate anions to bump chlorine to chloride. This still leaves the ammonia, hence my question. In some areas that use chloramines, you can use chlorine neutralizers, but then you end up dosing a certain amount of ammonia into your system. Ammonia (NH3) is more toxic than ammonium (NH4+) and the ration of ammonium to ammonia is mostly pH dependant. Combine this with doing filter maintenance, and you can see where the issues might pop up.