Different test Results

[Branespikin]

Ok thx. I look at that video. Yes that .1ml is the hot spot. Like mentioned earlier and automatic pipette might be the best way to get accurate results. I will get one of those and a magnetic stirrer just to have so i can. BE more accurate overall

 

[Rick Mathew]

Well yesterday i tried again to. BE super super careful of how much of Water i pit both sample and Rodi and made sure every bit if reagent was mixed correctly. This time i did get a more accurate reading. Salifert and Red Sea where bith at around 340 while Hanna came 461.
It took me 3 tries to get it to this close in my opinion its not worth the time and patience of getting every water drop/molecule in the vial making sure every single grain of powder reagent is in there and than not be sure if at the end i still got correct reading. Salifert and Red sea are simple enough and everytime were giving me a real close result without all the hassle. This checker is going in the closet

Just a note on the Hanna Calcium Checker. I have had very good success with this checker and have been using it for over 2 years. I made three changes that brought my Gage repeatability and reproducibility to less than 10% of the target range (100...350-450)

1) Purchased .3mL syringe...very accurate...You can find these from multiple suppliers

2) Use Hanna Deionized water (HI70436) and not my RODI water which has a small amount of calcium in it and is variable from batch to batch.

With the dilution ratio being so high and the water sample amount being so small these two changes took my R&R (repeatability and reproducibility) from between 30-40% (not good! almost random results) to less than 10% a very acceptable range for this test. My results have been validated by external testing sources so I feel confident in the measurement.

3) After the test is complete I rinse the vial and cap with the Hanna deionized water then fill the vial to the top with this water and store it this way until next use. Then on the next use I empty the vial do a quick rinse with the deionized water and proceed with the test.

IMO with good laboratory practices these checkers are great tools and do not rely on color change interpretation to make the measurement which in itself is a variable