Yet another test strip GH accuracy question.

[Tanked]

Like many of us, my test strips indicate a GH level of 300+ppm or 17.5 gpg (out of range).  Hard water has been offered up as to why some plants don't grow well, and other issues.

I just got off the phone with my municipal waterworks. I asked them what they thought my GH was.  My water comes from two different sources.  Their tests  indicates that my water is between 109-151 ppm or 6-9gpg.  The person on the phone was an aquarium keeper and presumably knew what I was referring to.  While she was looking up the information I tested my tap water, and got the 300+ppm result as expected.

Just in case the test strips were off, RO water tests came in at 0ppm.  Is it reasonable to think that the waterlines are adding that much hardness, or is it something else?

[nabokovfan87]

If there's ever a question, I always like to have a second test kit. Even if it's a strip, just to sanity check.

I find myself constantly flipping between "it could be 100-150" or "it's clearly way off the scale and 400+"

Sometimes the shades are just difficult to tell and the colorscales are slightly difficult to decipher.

The backup method is to use a colorblind simulator tool and shift the scale so you can see it in a different range or grayscale. There's a few ways to handle it, but generally speaking one of those may shed some light.

I don't think you'd off gas GH like that to alter the results of that particular parameter in question.

[Pepere]

I know my co op test strips reports significantly higher than my API test kit does on either GH or KH.  I think it is GH, but don't quote me…  I would have to re use a test strip to see which one is anomalous. 

The API also correlates very closely with expected results when dosing with Alkalinity buffer…

 

I would try a different test method.

[Tommy Vercetti]

First let me say that I love the aqurium test strips and that I use them often. But I have noticed that the gh is wildy inaccurate and always indicates much higher than what it should read. I have verified this using remineralized RO water and testing that against TDS meter and api liquid tests.

[Lennie]

If you ever consider a new gh test, I'm quite happy with my Sera one. I was getting so lost before starting to use it as well. 

[Tanked]

On 4/6/2023 at 11:43 AM, nabokovfan87 said:

I find myself constantly flipping between "it could be 100-150" or "it's clearly way off the scale and 400+"

Same here. In that situation I would write 125 in my notes and call it.  In my case, it is 301 for the GH.  I guess it is possible that the light violet I see is actually less than 300, but every color chart I've seen indicates otherwise. The fish are happy, so I'm not really concerned, just curious as to what the real number is.

Too Funny:  After spilling the entire 200 strips on the floor years ago, I stopped removing the the entire foil seal from the bottle.  Today while reading these replies, I tore the entire seal off of the ACO strips and found the laminated chart everyone talks about.  Kind of like finding a unicorn