Hannah Checker Sensitivity

[Averhoeven]

I'm about to start copper on my QT and had some questions about the Hannah Checker.
I recently had a weird scare, thought I had a copper contamination in my frag/coral QT that I posted in the reef chemistry forum.
The short question is, do you really have to baby the Hannah checker? Is it really that sensitive to bubbles, fingerprints, etc?
Here is the conclusion to my copper story I posted in reef Chem :

I just realized that at least some of my result may have been testing mistakes.
I added a second RO and another DI. I flushed it all through then ran a batch of RODI water which tested 0 TDS. Yet I still got 0.3ppm copper. That made me suspect the test.
I read through the manual carefully and finally understood that the machine was essentially measuring what seemed like particulate refraction. That lead me to be much more careful on my next test. I wiped the hell out of the outer glass, flicked and cleared every bubble I could find and just tested it after having an external timer at 45secs. That result was 0.03ppm.
I still did a huge water change and threw out my previously made saltwater and RODI to be safe.
Is the Hannah Copper test really that sensitive? I feel like I have to baby it.

 

[HotRocks]

IME, yes you have to follow the instructions EXACTLY to get accurate readings. It's a very precise instrument as long as you don't have particles in the sample, clean glass, no air bubbles etc.

I wouldn't worry about a .03ppm reading. The tolerance is +/-.05ppm. so essentially a .03ppm could still be zero.

 

[Averhoeven]

IME, yes you have to follow the instructions EXACTLY to get accurate readings. It's a very precise instrument as long as you don't have particles in the sample, clean glass, no air bubbles etc.

I wouldn't worry about a .03ppm reading. The tolerance is +/-.05ppm. so essentially a .03ppm could still be zero.

Thanks. I'd seen that tolerance limit before, so I was good with that followup result, but the original 0.3 in an invert tank had me panicking.
I'm used to using equipment in medicine that says it's sensitive, but designed with pretty high tolerances because of the idiot operator problem and I interpreted Hannah's warning in that context!