Saltert Akl Test. Variability between boxes. What to believe?!

[JayinToronto]

I've always used Salifert test kits for my alk testing. Things have been a little out of whack with my chemistry as of late as I'm battling a dino outbreak. My Dinoflagellate Experience - Prorocentrum. I've been testing and chasing around my numbers daily. I just picked up new Salifert kits for calcium, magnesium and alkalinity. The calcium and magnesium numbers are the same between the old and new kits. However my dKh with the old kit is 7.7 (from 8.3 yesterday) The new one its 11.7! What to believe??? Both of them have an expiration date of Aug 2023.

 

[taricha]

this amazing thread has all details you could want. (one tiny suggestion that I've seen cause inexplicable errors is that the different titration fluids for different tests are VERY different, so never use titration syringe in different tests)
https://www.reef2reef.com/threads/alkalinity-titration-endpoint-ph-salifert-endpoint-color.543556/

 

[JayinToronto]

Thank you for the link. Amazing amount of detail, and I’ll definitely take the information to heart when choosing my end point color. However, unless I’m missing something (which I probably am), I don’t think that post answers my question. I have 2 tests, both from the same company, both with the same expiration date, both performed by the same person with the same endpoints used, and the result is 4.1 dkh different between the two. Now I could accept a bit of difference and just use it to maintain stability, however the difference between 7.7 and 11.8 is just too much to accept. Not at all feeling comfortable and fearing for my tank. I also know something is wrong as my calcium consumption has basically gone to zero. I’ve tested it daily for the last 10 days (using 2 salifert kits and they both read the same) and my calcium has not budged from 480.

 

[Randy Holmes-Farley Verified Community Expert]

I'm not sure which is likely to be more accurate.

How much has alk changed during the time you say here was no calcium change?

 

[Cory]

Hey i had this problem years ago with salifert. Go to a pharmacist and they wikl weigh it for you:

1.1350 grams of baking soda in 1gallon of distilled water=10dkh