Frustrated with test kits

[kelrn98]

I have always used salifert kits for Ca and alk. a few months ago I bought some hanna checkers. I follow the instructions precisely. I always get significantly different readings with the two kits (ie Ca 410 with salifert and 510 with hanna, but dKH 8.3 with hanna and 9.8 with salifert). Has anyone else had similar experience? I don't know which test results to believe.

Any tips based on experience with these 2 brands to yield more accurate results? I have found that filling the hanna vials to the 10ml mark (meniscus at the 10ml mark) is a bit less than 10ml measured with syringe. Should I fill to the 10ml mark or add 10 ml measured with a syringe? Also the hanna checker came with plastic tips for the syringes. How does using or not using these tips affect the volume of added reagent or water sample? I am sure to wipe the vials of fingerprints/lint and let bubbles dissipate before placing in the checker. I wash vials out immediately after testing. all reagents are new, not expired, kept in 70-75 degree/dry environment. I use RODI with TDS 0 when called for by hanna checker.

I know this may be a wordy, difficult to understand post, but please read and offer suggestions if you are familiar with these kits as I am totally frustrated!

 

[phillrodrigo]

Check your salifert to the test solution it comes with. I hate the Hannah calcium that I have by far the worse thing I have bought ever. There's 2 parts of the test so I broke each half of the test down and tried multiple times with the same 2 bottles and got different numbers each time. So if it can read the same thing different each time I don't trust it. I like salifert atleast I can get back to back tests to read the same.

 

[Dan_P]

Test the Salifert reference standard. If the test results are off, it is either your technique or the reagents. You can use this reference standard in the Hanna checker to "check" on it.

 

[thegrun]

My Salifert alkalinity and my Hana alkalinity checker both read very close to each other and I've cross checked them several times over the past 5 years, so I suspect one of your regents is bad/old. I have never used a Hana Calcium checker, but it seems like all you hear are bad results from them. For calcium I would trust the Salifert results. For the Hana checkers it is critical that the glass vials are very clean and you follow the directions exactly.

 

[Eric45]

If you're salifert kit is over 6-9 months old, it could be the reagants. But otherwise, I've found the the test to be pretty reliable. Recently the alk take up tube to my doser pulled out and it was the salifert test that tipped me off both times.

 

[kelrn98]

Thanks to you all for your help. I will try the salifert solution tonight.