Conflicting Test Results

[Katch]

I picked up an API fresh water master today as my smaller Aqua One and Tetra tests were running low.

I thought I'd try them out side by side for comparrison on the tank I'm cycling at the moment.

My biggest concern is the Nitrite and Nitrate results.

My old tests have been showing Nitrite dropping to 0 in 24 hours along with ammonia. They have also been showing increasing levels of Nitrate to levels off the chart.

The API test is showing a 0 nitrate reading while the tetra shows in excess of 100ppm. API is also showing Nitrites off the chart 20 hours after last ammonia dose.

 

[Twinklecaz]

Test your tap water just to make sure the API kit isn't faulty. Other than that I'd say go with the API results.

 

[Katch]

The API Nitrite test is working fine - I tested my tap water and got 0 - i then added 12 drops of tank water and got a reading of .25ppm

I have no way of checking my Nitrate reading as I have no source of water guaranteed to contain nitrates.

 

[waterdrop]

My understanding is that while ammonia and nitrite(NO2) tests are relatively easy to make in a manner that will be reliable, nitrate(NO3) tests at the hobbyist consumer level are notoriously difficult to create in a way that will be accurate. A big part of the problem is that even analytical chemists have difficulty with NO3 tests (I've had discussions with an analytical chemist about this.) In the case of the API NO3 test, the difficulty can center around the 2nd reagent bottle (which has been written a lot about here.) Part of the 2nd reagent can precipitate out and if that happens, the solids can get stuck in the squirt tube or become caked and stuck at the bottle of the reagent bottle. Some find that they have to give the bottle a good whack on a hard surface a few times prior to doing the standard shake period before they will get a good test result.

In other cases we find that newcomers to testing just sometimes either don't read the instructions carefully enough or don't take them seriously. The NO3 tests -must- be done with all the shaking times observed. In fact, those shaking times are a bare minimum, according to my chemist friend. I also often recommend that one obtain one of those little kitchen timers that can hang around the neck so that you can do all the waits for tests while still moving about the house or getting tank mainenance accomplished (of course, some have these functions on their watches or whatnot.)

~~waterdrop~~