Alk testing discrepancy

[FishyFishFish]

I have every hanna tester. Low range nitrate is junk. Calcium tester is also junk. I use redsea dor both. The alk tester is touchy. The only sure way I have found is to take c1 pull it at c2, add reagent to c1, test that vial. Like wise take the phosphate tester, do the same. It will show a different result than using 2 separate glasses. Idk if it's contamination inside or outside the vial but I have personally found obscured results using separate containers. I use redsea to verify alk. It's normally spot on within 1dkh

Always use the same vial. Defects/differences in the glass will affect the result.

Also, as well as using the same vial, make sure that it is inserted into the colorimeter in the same orientation.

As for the Alk readings going off at the end of the bottle, Hanna states that it is good for 25 tests but there is more than 25ml of fluid in the bottle. I now mark the bottle and after 25 tests I throw it away - I never use the last drops in the bottle. I also ensure that the reagent bottle cap is only removed for the shortest period of time, and I have also stopped cleaning the syringe. With all of this done, my results are consistent enough for me to rely on them.

 

[jcolliii]

Get a good titration test kit for ALK. Salifert is really accurate for me testing against a standard. Tests take literally less than a minute. When you go looking for a PO4 test, I suggest staying away from Hanna as well - the ELOS kit is fantastic and super easy to read.

 

[Reef.]

I have every hanna tester. Low range nitrate is junk. Calcium tester is also junk. I use redsea dor both. The alk tester is touchy. The only sure way I have found is to take c1 pull it at c2, add reagent to c1, test that vial. Like wise take the phosphate tester, do the same. It will show a different result than using 2 separate glasses. Idk if it's contamination inside or outside the vial but I have personally found obscured results using separate containers. I use redsea to verify alk. It's normally spot on within 1dkh

I think that is the way you are meant to do it, the 2nd vial is a spare.