Question with Salifert's KH/Alk test UPDATED INFO 7/15/12

The test kit comes with a 3rd bottle labeled Alkalinity Check Solution 7.1 dKH +/- 0.3.
Is this used for checking the test's accuracy?
If so, I am assuming that I use this solution in substitute of the 4ml tank water, and the results should read 7.1 dKH +/- 0.3?
The reason I ask is, when I do this my result is 7.85 dKH?
Do I have a bad test kit or am I doing this wrong?
FYI the date on the box is 07-2015

 

Hi Vankirk
you are correct on the purpose of the solution so it states 7.1 +/- 0.3 thus your result should have been between 6.8 and 7.4

7.85 , if you did test correctly means the check solution is out of tolerance or the test kit is

but having used this brand of test kit for a couple of years now
I do know that when I started, I was adding a little bit more solution than I needed (making it turn pink and then a bit more pink LOL)

So it is possible that you overstepped the required amount of drops to get the colour change required

having said that

if your target was 9 and your dkh was 8.5 but test kit was reading 9 - you do not have an issue IMHO


also once you know by how much a test kit is out of tolerance, you can compensate for it IME

you could if you are concerned get your water tested by a 3rd party, and compare those results with your own test kit results

 

AGREE with mr. Steve

 

Thank you Steve for the quick reply.
So, "IF" lol I managed to do the test correctly then my tests results will actually be 0.75 HIGHER than the number I get?
Example tank water tested at 8.0 dKH but ACTUALLY it is 8.75 dKH correct?
I'm gonna go see if I still have an API bottle left and compare as you suggest.

 

Yes, if it is the test kit at fault - reading higher than it should be but not 0.75 - as max it should have read was 7.4 and it read 7.85 - so its somewhere beteen 0.45 and 0.75 out

but it is also possible that the calibration solution was out of tolerance
if for example there had been some evaporation from a slightly loose lid, then the Alkalinity would have been higher in that solution

but 8 or 8.75 - makes little or no difference in terms of DKH in your set up
IMHO
The main thing is knowing how accurate or outside of tolerance the test kit is and compensate until it is used up.

 

O.k. thanks again Steve. I am out of the API alk test so I think I'll pick up another Salifert kit and compare the tests of dKH and the calibration solution between the two.

 

I thought I would update everyone with my recent experiences with this test kit.

Last month I got a Hanna digital Alk checker. And since then I have been increasing my alk from 7.8 dKH to 10.0 dKH per the Hanna checker.

While I have been do this increase over the last few weeks I would also double check using the Salifert test kit. And what I've found was the Salifert test WAS READING TO HIGH.

At lower levels like 7.1 it would actually show 0.7 higher.
BUT at HIGHER levels it would be increasingly worse.
For example at 9.7 per Hanna the Salifert shows 12.0 dKH!

I'm not saying the Salifert test kits are flawed. But for me the ease of use and definitive answers that the Hanna Alk checker gives makes it one less thing for me to worry about.