I have identified a fix fot the Mag Hii783. Follow instructions for reagent A and the 5ml sample. When adding reagent B it requires 1.1ml. 1ml gives high readings and 1.2ml low readings. Hanna UK are aware of this fix and are dealing with itThere are several threads accumulating on the forums of people having issues w/new marine magnesium checker HI783. There are also some similar reports on the AskBRS facebook page--results several hundred points higher. I wanted to start a thread here in Hanna Instruments sub-forum to give Hanna a chance to see the reports of similar issues and address. I personally am despite about a dozen repeated tests using both factory instructions and varied testing procedures to ensure accuracy.
So Hanna emailed me back very quickly “Here are some tips the Aquariums manager put together which may be helpful. Repeatability issues are purely related to the quantity of reagent dispensed. In our experience, it just takes a little bit of practice getting used to dispensing the somewhat...www.reef2reef.comI'm, ok with high since all I'm looking for is above 1200. My tank is typically in the 1600 range anyways, and I never add mag. lol Sounds like you are best off not testing at all. lol Cheaper, easier, and you almost certainly will not get below 1200 ppm regardless of what you do. :)www.reef2reef.com
If you are having/have had issues w/this new device please post here.