Crazy test differences - proof of inaccuracy

[Eclyps19]

I've been struggling with myself for weeks now because my new tank has been easily processing 2-3ppm ammonia for quite a while, but my nitrites have been sky high with no signs of dropping. Even after a 70% WC, nitrites still seemed higher than was readable on my test kit. This is an API test kit, mind you, with an expiration date in 2023.

I went out and bought a Salifert test kit for nitrites, and I was shocked at the difference between the two. Here is a picture of the Salifert after the required 3 mins of waiting, compared to the API after only 1 minute (if I waited the full 5 minutes the color would be beyond what the chart shows).

Shoutout to brandon429 for continuing to remind me of how inaccurate test results can be, and to focus on the tank's ability to process ammonia (& time submerged!) rather than killing myself with potentially wildly inaccurate testing of nitrites...

 

[kintle]

I for weeks was trying to find out why I couldn't get nitrates below 20. I was fallow so adding the barest of food to the tank once a week for the snails but after multiple 50 percent water changes it wouldn't drop. Finally bought a red sea test kit to try and it showed up lighter than 2. Tossed the API since it wasnt working even though it wasnt expired. I dont get how they can be so far off but I'm sure all test kits could be.

 

[Clutch]

I had a similar issue with phosphates then I bought Hanna product and the rest is history. I love all of their products and the simplicity of them

 

[Randy Holmes-Farley Verified Community Expert]

Inaccurate test kits are the root cause of a large fraction of the unusual chemistry scenarios posted here.

 

[AdamNC]

For weeks my Red Sea PO4 Pro test kit tested 0ppm even though I was adding NeoPhos to raise it. I noticed corals browning and gha starting to get thick. So I picked up a Hanna ULN ppm meter, ended up reading 0.23ppm!!!

Lesson learned is if your kits say one thing but your tank is telling you another, get a second opinion. I stopped dosing NeoPhos and did water changes everyday for three days and now it’s down to 0.11ppm. Not where I want it but it’s going in the right direction.