GH Test kits

[svachon9]

So frustrated.  I have an API and pool kit that uses test strips and they both read about 180 ppm GH.  Which is considered moderately hard and I'd be fine with.  MY API drops kit give shows a 450ppm GH which is very hard.  Which one do I believe?

[nabokovfan87]

Can you take a photo of the test strip?  I actually had something similar happen, let me see if I can find the older thread.

[svachon9]

Bottom is GH

[Galabar]

I find it difficult to make accurate measurements of GH, KH, and pH with test strips.

Using the API GH and KH drop test kits, I've seen them work as I would expect after adding a certain amount of either Equilibrium or Alkaline Buffer to water.  So, I trust them to be more accurate.

On the other hand, I do use test strips very often to track nitrates and make sure that I have no ammonia or nitrites.

Another word of warning: when cycling a recent tank both the Tetra and ACO test strips showed zero ammonia, while the API test kit detected something in the range of 0.25 ppm.  So, at least for the ammonia test strips, if things go below around 0.5 ppm, you may get a zero reading.

 

 

[nabokovfan87]

On 10/29/2023 at 5:43 PM, svachon9 said:

Yeah, I had the same thing happen and I could not tell if it was slightly above 180 (slightly off the scale) or if it was ~100.  Ultimately I ended up getting the liquid test kit and then going ahead down that route.  If you have the liquid tests, it should be pretty reliable when it comes specifically to GH/KH.  The other ones (some of the strip based tests) can just be really difficult to interpret.

I would give it a re-test and if you are still having a major issue with the results, then take a water sample in somewhere and have the local store verify results.  You can also potentially have a kit that is a little off (wasn't stored properly) and might need to get a replacement.