API 1/2 Test Question

[DarthPadre]

For API tests like Ammonia or Nitrate where you are putting an even number of drops in, is it possible to split the test in half? Use 2 1/2 ML with only 4 (or 5) drops of each bottle? I understand that the smaller sample size makes the tolerance lower, but if you stay consistent with your tests it should work. Has anyone tried this? Can we all possibly split our costs in half for these items?

 

[DarthPadre]

I tried it with the Nitrate test. I tested a 5 ML sample using the 10 drop method and a 2 1/2 ML sample using the 5 drop method. I got two different colors. 10 ppm with the 5 ML (second time today for that exact test) and 15-20 ppm with the 2 1/2. My test kit may be suspect. At least with the Nitrate test I don't think the 1/2 method will produce accurate enough results. Once I create water with Ammonia in it I will test that kit and see if it's any different.

 

[Chris_A]

So I'm not sure about the "half" test method but my gut says no dice . Still though, please do post what you find trying it!

Now there is another method that is *similar* to what you are doing here. Basically it's a "low range" test. You cut the sample water with DI or Distilled water and divide your results by whatever factor you cut the sample.
For example:
if you have a 5 mL sample and you use 2.5 mL of sample water + 2.5 mL of DI (basically "pure" water)
Do your normal test.
Divide your results by 2 for the actual reading.

To be honest, I wish ALL test kits were calibrated like this. Then you could use a full 5 mL for a "high range", the 1/2 cut for standard and 1/4 cut for "low range".

Chris