API GH test kit issue / question

Two years ago I had this same issue and I'm wondering is it just bad luck or something else.

In March 2021 I was testing my GH but I quit when I was not getting a reading after 50 drops. I bought a new kit and it worked fine. My GH was where it had always been at 4 drops in my tap and and 12 drops in my African tank water. Fast forward to taday: I stopped adding drops at 30. Still no GH reading.

I was on Plantedtank.net and was told the API GH & KH tests wont last 2 years and need to to be replace regularly. I've never heard that before, but my experience tends to support that theory.

I don't test often and I'm always careful not to cause any contamination of the reagnts. I hate spending money on a test kit that I only use 6-8 times before it needs to be replaced.

 

Did you shake the bottle for a full 30 seconds before adding the drops? If not that can alter results.

 

Yes, I always shake the reagents. The instructions don't say it needs to be shaken, But I still do.

I will shake them much longer before testinhg to see if it makes a difference.

EDIT: Shook reagent for 45 seconds. Still no reading at 20 drops in my GH4 tap water.

 

Yes, I always shake the reagents. The instructions don't say it needs to be shaken, But I still do.

I will shake them much longer before testinhg to see if it makes a difference.

EDIT: Shook reagent for 45 seconds. Still no reading at 20 drops in my GH4 tap water.

What is the expiration date on the kit? I haven’t had a problem with any of mine until it got to around 6 months before the expiration date on the box.

 

Expiration date is Jan 2024, so not far off your 6 mo. So when I bought it in 3/21 it had less than 3 years of shelf life, which I guess isn't bad.

I never paid attention to the expiration dates on the KH and GH bottles. These 2 bottles which came in the same package have different expiration dates by about 2 years. GH exp date = Jan 2024 and the KH expires nin Dec 2025.

I usually check KH and GH about 2-3 times a year, so it frustrating to have to buy new reagent after only half dozen tests. That comes out to $2 US per test.

Are there other brands for these tests that others use and recommend?