The API 5 in 1 Test Strips will measure the Nitrate, Nitrite, pH, GH and KH parameters in your tank water. If this product does not appear to be working correctly, or at all, then you can take a look at this troubleshooting article from Aquarium Blueprints to see what you can potentially do.
1. To start off, you should make sure that the strips haven’t gone past the expiration date printed on the packaging.
If the product has expired, then it may not be able to accurately measure the Nitrate, Nitrite, pH, GH and/or KH levels.
In this case, you can either get a new container with non-expired strips or get a completely different tank water testing kit altogether.
2. Furthermore, try to avoid contaminating the strip before you drip it into the tank. Do not get any of the pads wet beforehand; if you did, then we recommend using a brand-new strip.
3. If the test strips still aren’t working, then you should make sure that you are following the directions correctly.
When it comes to dipping and then swirling, make sure that all five of the testing pads remain in constant contact with your tank water.
When taking the strip out of the tank, you need to do so with the pads facing upwards and without shaking off any excess water.
4. Furthermore, you should make sure that you are reading the test results properly. To do so, we recommend that you compare the testing pad to the color chart under bright lighting.
API recommends that you compare the GH and KH testing pads right away after you take the strip out of your aquarium water. For the Nitrate, Nitrite and pH pads, you need to wait for a minimum of 30 seconds after removing the strip from the tank before you compare these to the color chart.